Hitachi Koki Co., Ltd.

Koki Holdings Co., Ltd.

Takahiro Hirai

Tomomasa Nishikawa

Shingo Kosugi

Tomoyuki Kawahara

Takamoto Horiuchi

Masato Sakai

Masanori Okada

Akira Matsushita

Shinichi Kakefuda

Katsumi Kurihara

Takeshi Takeda

Yoshikazu Yokoyama

Tatsuya Ito

Yuta Noguchi

Tsukasa Suzuura

Tetsuhiro Harada

Shinichiro Sato

Satoshi Hotta

Fumikazu Hirasawa

Hiroshi Ohira

Yang Li

Providing an electric tool with excellent cooling efficiency. An electric tool includes: a housing; a motor; a fan; a sensing portion; a switching portion; and a circuit board. The motoris accommodated in the housing. The motorincludes a stator, a rotor, and a rotating shaft. The rotoris rotatable relative to the stator. The rotating shaftis rotatable together with the rotor. The fanis configured to generate a cooling air flow inside the housing. The sensing portionis configured to detect a rotated position of the rotor. The switching portioncontrols a rotation of the rotor. The sensing portionand the switching portionare mounted on the circuit board. The stator, the fan, the sensing portion, the switching portion, and the circuit boardare arranged in the housingalong an axial direction of the rotorin the order of the fan, the sensing portion, the circuit board, the switching portion, and the stator

Electric tool

To provide a rotary impact tool capable of: suppressing a rise in temperature in a motor or switching elements and a current flowing in the motor or switching elements while suppressing a degradation in tightening performance; and improving operability. The rotary impact tool includes: a motor; an end-bit holding part driven by the motor; an impact mechanism provided on a drive transmission path from the motor to the end-bit holding part and configured to intermittently produce rotary impacts, the rotary impacts transmitting a drive force of the motor to the end-bit holding part; a switching element configured to change a voltage supplied to the motor; and a control unit controlling the switching element. The control unit is configured such that the voltage supplied to the motor begins to gradually rise within a period of time from a timing when a first rotary impact ends to a timing when a second rotary impact subsequent to the first rotary impact starts.

Rotary impact tool

A portable working machine including: a driving source; a main body including the driving source; a handle joined with the main body; a fixing portion provided to one of the main body or the handle; and a vibration-proofing mechanism including an elastic body, the handle joined with the main body with the vibration-proofing mechanism and the fixing portion interposed therebetween; wherein the elastic body of the vibration-proofing mechanism is fixed to a first side of the fixing portion, and a stopper portion configured to come into contact with the other of the main body or the handle to regulate a movement amount of the handle is provided at a second side of the fixing portion, which is opposite to the first side of the fixing portion.

Portable working machine

A working machine has an oil groove communicating a pump chamber with a gear chamber, and a small amount of oil is delivered to the gear chamber when oil is discharged from the pump chamber. Thus, the oil adheres to the outer peripheral surface of a rotating pump shaft and is kept remaining between a pump case and the pump shaft. Therefore, the viscosity is increased and a pressure loss between the pump chamber and the gear chamber is increased. Accordingly, the airtightness can be maintained, and the stable and inexpensive oil pump mechanism requiring less man-hour can be realized without depending on the accuracy of a gap between the pump case and the pump shaft. Since oil is kept remaining on the outer peripheral surface of the pump shaft, it is possible to prevent the pump case from being worn out and to improve the durability of components.

There is provided a four-cycle engine which can appropriately circulate oil in an engine regardless of a tilted condition with a simple structure. A crankcase () of a four-cycle engine () has a crank room () which rotatably supports a crankshaft () and an oil room () which is provided adjacent to the exterior of the crank room (). The crankcase () also has partition walls () and () which partition the interior of the crankcase () into the crank room () and the oil room (), respectively, and a communication path () which communicates the crank room () with the oil room (). The partition walls () and () each has a cross section formed in a substantially V shape, and the communication path () is formed at an apex between the partition walls () and ().

Four-cycle engine, bush cutter and engine-driven tool having same

An impact force is transmitted to a tip end tool due to the changes of the air pressure within an air chamber generated by the reciprocal operation of the piston within a striker. The attachment portion of a tip end tool holding member for holding the tip end tool to a cylinder casing is sandwiched between buffers disposed in the two directions of the axial direction of the tool thereby to elastically support the tip end tool holding member to be movable in the two directions of the axial direction of the tool.

Striking tool

Engine

Engine blower

Growing community of inventors

Hitachinaka, Japan

Takahiro Hirai