Makita Corporation

Kiyoshi Aoyama

Masanori Higashi

Hitoshi Suzuki

Hidenori Nagasaka

Masaaki Fukumoto

Motohiro Omura

Nobuyasu Furui

Kenji Abe

Masayoshi Okumi

Kenji Shibata

Takashi Momose

A vibration driver drill as an electric power tool includes a brushless motor that includes a rotor and a sensor circuit board that detects a rotation of the rotor. The rotor includes a tubular rotor core and four permanent magnets held in the rotor core so as to extend in an axial direction of the rotor core. The sensor circuit board is adjacent to a front-end part (first end portion) of the rotor core. The rotor core is provided with a recessed groove on a side surface outward between the mutually adjacent permanent magnets. The recessed groove extends from the front-end part in the axial direction of the rotor core without reaching a rear-end part (second end portion) facing the front-end part.

Electric power tool

An electric working machine may include a brushless motor and a motor controller. The motor controller may include three upper switching elements, three lower switching elements, and a control unit. The control unit may be configured to execute a short-circuit braking operation for applying a braking force to the brushless motor by bringing the three upper switching elements into a non-conductive state and bringing the three lower switching elements into a conductive state. The control unit may be configured to start the short-circuit braking operation at a predetermined timing. When the short-circuit braking operation is started at the predetermined timing, polarities of induced voltages of first to third phase terminals of the brushless motor are reversed by a time when an electrical angle of the brushless motor increases by 180 degrees from the start of the short-circuit braking operation.

Electric working machine and motor controller

An electric power tool includes a brushless motor as a driving source. The brushless motor includes a stator and a rotor. The stator includes coils wound around in three phases. In a wire winding method of the coil of the stator, when the number of slots per phase is N, the number of series of the coils per phase is A, and the number of parallel of the coils per phase is B, a relation of N=A&#xd7;B (note that, N is a natural number of 3 or more and 10 or less, A is a natural number of 1 or more, and B is a natural number of 2 or more) is satisfied.

The present application discloses an electric working machine. The electric working machine includes a motor including a stator. The stator includes: a stator core haring a plurality of tooth portions radially extending along a radial direction; and a first coil, a second coil, and a third coil wound on the tooth portions. A start end of the first coil and a finish end of the second coil, a start end of the second coil and a finish end of the third coil, and a start end of the third coil and a finish end of the first coil are led out within a range of 200 degrees from the stator.

Electric working machine

The present application discloses an electric working machine. The electric working machine includes: a motor including a rotor; a sensor board including a magnetic sensor for detecting magnetic variation due to rotation of the rotor; and a housing which contains the motor and the sensor board. in the electric working machine, the sensor board does not cover an entire circumference of the rotor. In the electric working machine, the sensor board has a portion covering the rotor, and a portion not covering the rotor.

A hand-held power tool includes a motor having a stator and a rotor, the motor being configured to rotate the rotor at a speed of at least 40,000 rpm, an output shaft directly driven by the rotor, a tool accessory shaft configured to support a tool accessory, and a two-stage speed reducing transmission operably connecting the output shaft to the tool accessory shaft. The two-stage speed reducing transmission is configured to drive the tool accessory shaft at a rate less than the rotor speed, for example, at a rate less than or equal to 37.5% of the rotor speed.

Growing community of inventors

Anjo, Japan

Kiyoshi Aoyama