Hitachi Koki Co., Ltd.

Koki Holdings Co., Ltd.

Hiroshi Haga

Masato Sakai

Hideyuki Tanimoto

Hideyuki Hashimoto

Nobuhiro Takano

Masanori Okada

Takeshi Taniguchi

Kazutaka Iwata

Yoshitaka Suzuki

Toshiaki Koizumi

Naoki Tadokoro

Atsuyuki Kikuchi

Seiichi Kodato

Shinichirou Satou

Tsukasa Suzuura

Shingo Yamazaki

Kuniaki Kanbe

Tomoya Ikeda

Kazuhiro Suzuki

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.

Electric tool

A power tool includes a housing, a motor, an output unit, and a circuit board unit. The motor is accommodated in the housing and has a rotational axis extending in a top-bottom direction. The output unit is disposed above the motor and extends in a front-rear direction. A power cable is configured to be connected to a power source and is connected to the circuit board unit. The circuit board unit is accommodated in the housing. The circuit board unit comprises a switching element for driving the motor, and a rectifying device configured to rectify an alternating current from the power source to a direct current. The circuit board unit is disposed below the motor and extends in the front-rear direction in the housing.

Power tool having circuit board

A power tool includes a brushless motor, a switching element, a power cable a rectifying device, a heat releasing member. The switching element controls a drive of the brushless motor. The power cable supplies an electric current to the brushless motor from power source. The rectifying device rectifies the electric current from the power cable. The heat releasing member is connected to the switching element and the rectifying device in order to enhance a cooling efficiency for the same.

A reciprocating tool () includes a housing (), a driving source (), a reciprocation conversion unit (), &#x2014;and a vibration reduction mechanism (). The driving source is accommodated in the' housing. The reciprocation conversion unit () is supported by the housing and is configured to convert a driving force of the driving source into a reciprocating motion for providing a tool bit () movably supported to the housing with a reciprocating motion. The vibration reduction mechanism () includes a shaft (), a weight (), a support member (), and a urging portion (). The shaft i()s supported by the housing and extending in a direction perpendicular to directions of the reciprocating motion of the tool bit () t and has an axis. The weight () is located away from the shaft () and is swingable in a swinging direction. The support member () swingably supports the weight () about the axis of the shaft (). The urging portion () urges the weight () toward a prescribed position of the weight in the swinging direction with respect to the housing.

Reciprocating tool

Portable electric hammer drill

An engaging portion, formed at an axial end of an intermediate member, is engageable with a slide sleeve. A cylinder has an elongated hole with an axial length longer than a shifting distance of the intermediate member. The slide sleeve includes an annular member and a slide member. The annular member has an inner cylindrical wall engageable with the engaging portion of the intermediate member and a projection extending in a radially outward direction passing through the elongated hole beyond an outer surface of the cylinder. The slide member is coupled around the outer surface of the cylinder and is slidable in the axial direction of the cylinder. One axial end of the slide member, positioned closer to a working tool, is engaged with the projection of the annular member. The other axial end of the slide member is urged toward the working tool by an urging member.

Hammer drill

Growing community of inventors

Ibaraki, Japan

Hiroshi Haga