Brushless motor, wiper apparatus, motor apparatus, and control method for motor apparatus

Abstract

A brushless motor ( 18 ) which supplies currents to coils (U 1 , U 2 , V 1 , V 2 , W 1 , and W 2 ) and rotates a rotor ( 27 ), the brushless motor comprising a control apparatus ( 37 ) which switches and selectively executes: first energization control to start energization to the coils (U 1 , U 2 , V 1 , V 2 , W 1 , and W 2 ) at first timing, and to continue the energization for a first period to control the rotation number of the rotor ( 27 ); and second energization control to start energization to the coils (U 1 , U 2 , V 1 , V 2 , W 1 , and W 2 ) at second timing advanced by an electric angle with respect to the first timing, and to continue the energization for a second period longer than the first period to control the rotation number of the rotor ( 27 ).

What is claimed is: 
     
         1 - 13 . (canceled) 
     
     
         14 . A brushless motor which supplies a current to a coil and rotates a rotor, the brushless motor comprising a control unit which switches and selectively executes:
 first energization control to start energization to the coil at first timing, and to continue the energization for a first period to control the rotation number of the rotor; and   second energization control to start energization to the coil at second timing advanced by an electric angle with respect to the first timing, and to continue the energization for a second period longer than the first period to control the rotation number of the rotor.   
     
     
         15 . The brushless motor according to  claim 14 , wherein the second timing is advanced by an electric angle 30° with respect to the first timing. 
     
     
         16 . The brushless motor according to  claim 15 , wherein the first period is an electric angle 120°, and the second period is equal to or more than an electric angle 135° and equal to or less than an electric angle 165°. 
     
     
         17 . The brushless motor according to  claim 14 , further comprising a stator disposed around the rotor,
 wherein the rotor has:   a rotor shaft having a rotor core attached to an outer peripheral surface thereof; and   four permanent magnets disposed on the outer peripheral surface of the rotor core along a circumferential direction of the rotor shaft,   wherein the stator has six teeth disposed at intervals in the circumferential direction of the rotor shaft, the coil being wound around the teeth.   
     
     
         18 . A wiper apparatus, comprising:
 the brushless motor according to  claim 14 ; and   a wiper arm which receives power from the rotor of the brushless motor, and which is moved so as to wipe off a window glass of a vehicle.   
     
     
         19 . The wiper apparatus according to  claim 18 , comprising: a mode switching unit which switches and selects one of a low-speed mode to move the wiper arm at a speed determined in advance; and a high-speed mode to move the wiper arm at a speed faster than the low-speed mode,
 wherein the control unit executes the second energization control when the high-speed mode is selected.   
     
     
         20 . A motor apparatus which supplies currents to a plurality of coils and rotates a rotor, the motor apparatus comprising:
 a plurality of switching elements which separately turn on or off current supply paths connected to the coils;   a plurality of sensors which are different in phase from each other, provided in a rotation direction of the rotor, and detects a phase of the rotor in the rotation direction to generate output signals;   a signal correcting unit which uses an output signal of any one sensor among the sensors as a reference signal, and corrects the output signal of the other sensor; and   an element control unit which separately turns on or off the switching elements on the basis of the reference signal and the corrected output signal.   
     
     
         21 . The motor apparatus according to  claim 20 , wherein
 the element control unit switches and selectively executes:   first energization control to start energization to the coils at first timing to control an output of the rotor; and   second energization control to start energization to the coils at second timing advanced by a predetermined electric angle with respect to the first timing to control the output of the rotor.   
     
     
         22 . The motor apparatus according to  claim 20 , wherein
 the element control unit executes third energization control to continue energization to the coil for the time longer than the time in which the energization to the coil is continued in the second energization control.   
     
     
         23 . The motor apparatus according to  claim 20 , further comprises a control board to which the switching elements, the sensors, the signal correcting unit, and the element control unit are attached. 
     
     
         24 . The motor apparatus according to  claim 20 , further comprising a stator disposed around the rotor,
 wherein the rotor has:   a rotor shaft having a rotor core attached to an outer peripheral surface thereof; and   four permanent magnets disposed on the outer peripheral surface of the rotor core along a circumferential direction of the rotor shaft,   wherein the stator has six teeth disposed at intervals in the circumferential direction of the rotor shaft, the coil being wound around the teeth.   
     
     
         25 . The motor apparatus according to  claim 20 , further comprising a power transmitting mechanism that transmits torque of the rotor to a wiper arm which wipes off a window glass of a vehicle. 
     
     
         26 . A control method for the motor apparatus according to  claim 20 , the motor apparatus controlling an output of a rotor, the control method comprising:
 a first step of controlling the output of the rotor by using an output signal of any one sensor among the sensors as a reference signal, and correcting the output signal of the other sensor; and   a second step of separately turning on or off the switching elements on the basis of the reference signal and the corrected output signal.