Hitachi Koki Co., Ltd.

Koki Holdings Co., Ltd.

Hitachi Koki

Koki Holdings Kabushiki Kaisha

Kazutaka Iwata

Nobuhiro Takano

Katsuhiro Oomori

Toshiaki Koizumi

Tomomasa Nishikawa

Kenichirou Yoshida

Yoshihiro Komuro

Atsushi Nakagawa

Hironori Mashiko

Hideyuki Tanimoto

Shinji Watanabe

Hiroki Uchida

Mizuho Nakamura

Yoshio Iimura

Naoki Tadokoro

Hayato Yamaguchi

Yasutaka Shimizu

Kenro Ishimaru

Tetsuhiro Harada

Saroma Nakano

Kazuhiko Funabashi

Shinichi Sakamoto

Shinki Ohtsu

Chikai Yoshimizu

Eiji Nakayama

Junichi Toukairin

Tomoyoshi Yokota

Takuya Yoshinari

Shinichirou Satou

Yuta Noguchi

Yutaka Ito

Takahiro Ookubo

Hiroshi Haga

Tomoaki Sudo

Satoshi Abe

Ken Inui

Shogo Shibata

Shiniki Otsu

Shinji Watabe

Shinki Otsu

An electric power tool includes: a brushless motor having a plurality of stator windings and configured to rotate in accordance with voltages applied to the plurality of stator windings, an induced voltage being generated in accordance with a rotation of the brushless motor; a rectifier circuit configured to rectify an AC voltage; a smoothing capacitor configured to smooth the AC voltage rectified by the rectifier circuit to a pulsation voltage having a maximum value larger than the induced voltage and a minimum value smaller than the induced voltage; and an inverter circuit configured to perform switching operations to output the pulsation voltage to the plurality of stator windings by rotation.

Electric power tool

A power tool includes: a rechargeable battery; a motor; a drive circuit; an operation unit; a battery state detection circuit; a control circuit; and an interruption circuit. The battery state detection circuit detects a battery voltage, and when the detected battery voltage is lower than or equal to a prescribed voltage, the battery state detection circuit outputs a low-voltage signal. The control means outputs a control signal to the drive circuit instructing to drive the motor when the operation unit is operated and halts the output of the control signal to the drive circuit instructing to halt driving the motor in response to the low-voltage signal. The interruption circuit outputs an interruption signal to the drive circuit in response to the low-voltage signal to thereby interrupt the drive circuit and halt driving the motor irrespective of whether or not the control signal is outputted to the drive circuit.

Power tool

An electric tool capable of achieving inhibition of reaction due to braking in good balance with inhibition of voltage jumping due to regenerated energy is provided. A grinder () is provided with a motor (), an inverter circuit () for supplying electric current to the motor (), and a controller () for controlling the inverter circuit (). When generating an electric braking force on a motor (), the rotation speed of which exceeds a specified rotation speed, the controller () performs a first braking control of continuously turning on lower arm-side switching elements (Q-Q) of the inverter circuit (), after which the controller performs a second braking control of repeatedly turning on and off the lower arm-side switching elements (Q-Q).

Electric tool

An impact tool and method can include: a motor; a trigger; a controller configured to control driving power supplied to the motor using a semiconductor switching element according to an operation of the trigger; a striking mechanism configured to drive a tip tool continuously or intermittently by rotation force of the motor, the striking mechanism including a hammer and an anvil. The controller drives the semiconductor switching element at a high duty ratio when the trigger is manipulated. The motor can be driven so that the duty ratio is lowered before a first striking of the hammer on the anvil is performed and the first striking is performed at a low duty ratio lower than the high duty ratio.

Impact tool and method of controlling impact tool

An impact tool includes: a motor; a trigger; a controller configured to control driving power supplied to the motor using a semiconductor switching element according to an operation of the trigger; a striking mechanism configured to drive a tip tool continuously or intermittently by rotation force of the motor, the striking mechanism including a hammer and an anvil. The controller drives the semiconductor switching element at a high duty ratio when the trigger is manipulated. The motor is driven so that the duty ratio is lowered before a first striking of the hammer on the anvil is performed and the first striking is performed at a low duty ratio lower than the high duty ratio.

In order to provide an electric tool with good operability that can extend the life of and suppress breakage of a switching element for controlling energization of a brushless motor, a control unit (), after an operation switch () is turned off, does not immediately turn off an inverter circuit () (does not set the duty of a PWM signal to 0), and instead normally operates the inverter circuit () with a low-duty PWM signal and waits until a rotation speed of a brushless motor () reaches a predetermined rotation speed or less to turn off the inverter circuit () (to set the duty of the PWM signal to 0).

An electric tool including a motor configured to be driven by a PWM control of a semiconductor switching element by using a power supply, a power transmission mechanism configured to transmit a rotation of the motor to an end tool, and a controller configured to control a rotation of the motor by a duty ratio of a PWM signal, wherein the controller is configured to set the duty ratio to a reference duty ratio less than 100% when a voltage of the power supply applied to the electric tool is within a predetermined range including a rated voltage of the electric tool, and wherein the controller is configured to drive the motor by setting the duty ratio to be higher than the reference duty ratio when the voltage of the power supply applied to the electric tool is lower than the predetermined range.

To provide a power tool capable of suppressing torque ripple and reducing power consumption without demagnetizing the permanent magnets in the rotor. The power tool includes a brushless motor, converting means, voltage detecting, and means conduction switching means. The brushless motor includes: a stator including a plurality of windings; and a rotor rotatable relative to the stator. The converting means is configured to convert an AC voltage supplied from an AC power supply into a varying DC voltage. The voltage detecting means is configured to detect the varying DC voltage. The conduction switching means includes an output line for applying the varying DC voltage to the plurality of windings. The conduction switching means is configured to perform: sequentially switching at least one winding to be applied with the varying DC voltage among the plurality of windings to rotate the rotor; and changing number of conducting windings on the basis of the varying DC voltage, the number of conducting windings being number of the at least one winding to be applied with the varying DC voltage.

The purpose of the present invention is to use a motor with as high an output as possible to complete tightening operations at a high speed while limiting continuous drive output. In a power tool having a plurality of impact operation modes, the motor thereof is controlled at a 100% duty cycle so as to rotate at a high speed in the period between pulling of a trigger and starting of an impact operation (-), and the duty cycle is changed to a low duty cycle matching the appropriate operation mode after an impact by an impact mechanism is started and a predetermined stroke is performed so that the motor is driven at the low duty cycle until the trigger is returned (arrow-). The switching of the duty cycle is performed when the current flowing to the motor exceeds a threshold (I).

An electric tool includes: a motor configured to be driven by PWM controlling a semiconductor switching element; a trigger configured to adjust startup and rotation of the motor; a changeover switch configured to switch a rotation direction of the motor between a forward rotation and a reverse rotation; a power transmission mechanism configured to rotate a tip tool by the motor, and a controller configured to control rotation of the motor. When the reverse rotation is set by the changeover switch, the controller PWM controls the semiconductor switching element at a high duty ratio after the trigger is pulled to drive the motor, and thereafter drives the motor at a state where the high duty ratio is changed to a low duty ratio.

A power tool includes: a power source (); a tip tool (); two switches (SWSW); and a control unit (). The tip tool () is configured to be driven by the power source (). The two switches (SWSW) are configured to be turned on for activating the power source (). The control unit () is configured to control the power source () in accordance with on/off of the two switches (SWSW), and operate if at least one of the two switches (SWSW) is turned on.

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Hitachinaka, Japan

Kazutaka Iwata