Hitachi Koki Co., Ltd.

Mitsuo Ogura

Yasuo Sasaki

Mitsuyuki Ishikawa

Yasuki Ohmori

Takuhiro Murakami

Hiroto Inagawa

Yoshikazu Yokoyama

Junichi Kamimura

Satsuo Sato

Naoya Eto

Yoshimitsu Kawasaki

Takeshi Toyoshima

Juurou Kobayashi

Nobuhiro Takano

Shigeru Shinohara

Akira Uno

Michio Wakabayashi

Mitsuhiro Sunaoshi

Tsukasa Suzuura

Toshifumi Kubota

Hiroyasu Ishikawa

Yuuichi Satou

Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission keycomposed of high-strength plastic is provided between an output shaftand a gearand a plane or a V-groove is formed on each of the output shaftand the gearcontacting the power transmission key

Electric power tool

Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission key composed of high-strength plastic is provided between an output shaft and a gear , and a plane or a V-groove is formed on each of the output shaft and the gear contacting the power transmission key

A motor and a power transmitting mechanism are accommodated and supported in a two-piece housing unit separable into first and second housings. An air tank is defined by an outer surface of the second housing and an inside surface of a third housing provided on a recessed outer surface of the second housing.

Portable compressor

An air motor has a rotor rotatable in response to the pressure of pressurized air. A cylindrical rotary member is connected to the air motor for causing a rotation in synchronism with the rotation of the rotor. A rotary slider is slidable in the axial direction along the inner cylindrical wall of the rotary member. A rotational force transmitting mechanism is provided for transmitting the rotation of the rotary member to the rotary slider. A shaft has one end fixed to the rotary slider and the other end equipped with a piston and a driver bit holder. The rotational and axial motion of the rotary slider is transmitted to a driver bit held in the driver bit holder. And, a cylinder guides the axial slide movement of the piston responsive to the pressure of pressurized air applied on a pressure-receiving surface of the piston.

Pneumatically operated screw driver

A power screw driver includes a clutch mechanism composed of a coiled clutch spring so designed as to entangle a drive shaft member and an output shaft member to connect them together, thereby enabling the drive and output shaft members to rotate in unison. By the use of the coiled clutch spring, the clutch engaging operation is achieved smoothly and silently without accompanying impact blow or shock, thereby securing reliable transmission of a torque from the drive shaft member to the output shaft member. The coiled clutch spring may be activated only when the drive shaft member is rotating in the forward direction, in which instance a one-way clutch is used to undertake transmission of the torque when the drive shaft member is rotating in the reverse direction. As an alternative, a single clutch spring may be used to undertake transmission of the torque in the forward and reverse rotational directions. Alternatively, two coiled clutch springs each provided for one rotational direction may be used.

Power screwdriver and clutch mechanism used therein

A pneumatically operated screw driver having a moving unit rotatable about its axis by rotation of a rotor and movable axially by a pneumatic pressure. The moving unit includes a spline shaft supported by the rotor through a ball spline, and a drive bit aligned with the spline shaft and engageable with a head of a screw. The spline shaft has an annular flange portion. A movable piston is disposed concentrically over the spline shaft and movable in an axial direction thereof with respect to the spline shaft. A spring is disposed over the spline shaft and is interposed between the movable piston and the flange portion. A stop member is provided to a rotor or a frame body. If pneumatic pressure is applied to the movable piston, the latter is axially moved downwardly and is brought into abutment with the stop member. The spline shaft is also moved axially slightly after the movement of the movable piston. The shrinkage of the spring will generate shape-restoration force thereof to further move the spline shaft after the stop of the movable piston.

An improved structure of an impact screwdriver is provided which achieves a low-noise screw-driving operation. The impact screwdriver includes a clutch assembly for transmitting torque provided by a motor to a tool bit. The clutch assembly includes a toque-transmitting member, a torque-outputting member, and a clutch coil spring. The clutch coil spring is selectively wound around the torque-transmitting member and the torque-outputting member according to a rotational difference therebetween to establish torque transmission for providing the torque to the tool bit intermittently.

Low-noise impact screwdriver

To charge a battery having a different number of cells connected in series with a relevant charge current, the number of cells of the battery is firstly determined and a current level corresponding to the number of cells is determined in view of the potential of the charger. The charge current having a level substantially equal to the thus determined current level is flowed in the battery.

Universal battery charger chargeable with relevant current dependent on

A vacuum pump includes a rotatable cylinder rotatably disposed coaxially around an inner stationary cylinder and in an outer stationary cylinder. The rotatable cylinder has a plurality of recesses defined in inner and outer circumferential surfaces thereof. The outer stationary cylinder has a helical groove defined in an inner circumferential surface thereof. The inner stationary cylinder has a helical groove defined in an outer circumferential thereof. The rotatable cylinder is rotated by a motor to deliver a gas axially along the helical grooves. The recesses are effective to produce turbulent flows in the gas to increase the rate at which the gas is discharged. The recesses have an axial length smaller than the transverse width of helical threads on the outer circumferential surface of the inner stationary cylinder and the inner circumferential surface of the outer stationary cylinder, to minimize any gas leakage across the helical threads.

Vacuum pump with helically threaded cylinders

A molecular drag pump for delivering a gas under molecular flow conditions comprises a pair of parallel, helically threaded rotors rotatably mounted in a stationary housing. The rotors have respective helical threads and respective helical grooves, and are held in close mesh with each other. The helical threads are helically inclined in one direction to the axes of the rotors, and have a flank angle such that the helical threads are closely received in the respective helical grooves while keeping the threads out of contact with each other. The rotors are rotated in one direction about their respective axes to move a gas introduced through an inlet port toward an exhaust port axially along the rotors.

Growing community of inventors

Hitachinaka, Japan

Mitsuo Ogura