Mitsuba Corporation

Tomohiko Annaka

Naoki Kojima

Masaaki Kimura

Hiroto Tanaka

Tamotsu Iwazaki

Junya Kitazawa

Toshiyuki Kimura

Takeshi Kanai

Hirokazu Shoda

Toru Furusawa

Tomofumi Kobayashi

A brushless motor () which supplies currents to coils (U, U, V, V, W, and W) and rotates a rotor (), the brushless motor comprising a control apparatus () which switches and selectively executes: first energization control to start energization to the coils (U, U, V, V, W, and W) 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 coils (U, U, V, V, W, and W) 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 ().

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

Since a shape of a statoris made mirror symmetric with respect to a rotoras a 4-pole/6-slot type, rotational deflection of the rotorcan be suppressed. As the minimum number of poles and the minimum number of slots, which can suppress the rotational deflection of the rotor, a frequency of magnetic noises approaches a frequency of mechanical noises. Thus, it is possible to integrate the whole noises generated by the DR-side wiper motorinto a low frequency range thereof, and to make the acoustic sensitivity (dB) of a vehicle interior smaller. Since the statoris fixed inside a housingand mounting legs fixed to a vehicle body fixed portion are provided in the housing, the stator, which is a source of the magnetic noises, can be fixed to a vehicle via only the housing. Therefore, a brushless wiper motor with quietness improved further can be designed.

Brushless wiper motor

A motor case () in which a stationary portion () is fixed, and a gear case () in which a gear mechanism (SD) is accommodated are made of aluminium, most heat generated from the stationary portion () at the time of actuation of a brushless wiper motor () can be directly dissipated outside from the motor case (). That is, compared with conventional technique, heat transmitted to the motor case () can be efficiently dissipated outside, and the motor case () does not reach high temperature. Therefore, as a matter of course, reduction in size and weight can be achieved, suppression of electromagnetic noise can be achieved, and heat-resistance strength can be enhanced. Expensive components capable of resisting high temperatures are not required, and reduction in manufacturing cost can be achieved.

A brushless motor comprises: a statorhaving armature coils, and; a rotorwhich is rotated by a revolving magnetic field; and a switching element, wherein the brushless motor has a rotation number control unitwhich switches between low-speed and high-speed mode, wherein in the low-speed mode, the rotation number control unitsupplies current to the armature coils, andat predetermined energization timing and controls a duty ratio to control the rotation number of the rotor, and in the high-speed mode, the rotation number control unitsupplies current to the armature coils, andat energization timing advanced from the energization timing for the low-speed mode, thereby performing field weakening control of weakening the revolving magnetic field from that of the low-speed mode to control the rotation number of the rotor

Growing community of inventors

Gunma, Japan

Tomohiko Annaka