Hitachi Koki Co., Ltd.

Hitachi, Ltd.

Shigeru Shinohara

Eiji Nakayama

Nobuhiro Takano

Shun Suzuki

Masateru Niyada

Hiroaki Orikasa

Kazuhiko Funabashi

Chikai Yoshimizu

Atsushi Nakagawa

Takahiko Shimada

Toshio Mizoguchi

Junshin Sakamoto

Houng Joong Kim

Hiroshi Hayasaka

Yoshitaka Niinai

Yoshio Iimura

Kazuyoshi Tokunaga

Kenrou Ishimaru

Mitsuo Ogura

Toshiaki Uchida

Hidekazu Harada

Yoshimasa Hayama

Hiroyasu Ishikawa

Mitsutoshi Yotsuyanagi

Shigeru Moriyama

Daisuke Kakegawa

Akio Nagata

Takahito Ishizuka

Tatsuo Innami

Norihisa Sagawa

Syuichi Okada

Junichi Sudo

A dust collector includes: a motor functioning as a driving source; a drive unit for driving a motor; a dust collection fan rotated by the motor; a head section for accommodating the dust collection fan; a switch provided on the head section to control the starting of the motor; a tank section located below the head section, for accommodating dust conveyed by the dust collection fan, the tank section having a connecting portion; a duct hose having one end and the other end, the one end attached to the connecting portion, the other end being detachable from a portion of a power tool; a remote-control transmitter for transmitting a signal; and a remote-control receiver for receiving the signal from the remote-control transmitter to control the drive unit to start or stop the motor.

Dust collector

A power tool includes a linear motor and a maximum reciprocal movement amount setting unit. The linear motor has a movable member driven to move reciprocally and a tool connector for connecting work bits to the movable member. The maximum reciprocal movement amount setting unit is for setting maximum reciprocal movement amount at which the linear motor drives movement of the movable member to a selected one of a plurality of maximum reciprocal movement amounts. Also, a position information region is provided on the movable member. A movable member region detector detects the movable member position information region of the movable member and a control unit sets, as the initial position of the movable member, position of the movable member at the time the movable member region detector detects the movable member position information region.

Power tool driven by linear motor

A power tool has a linear motor which includes a movable element having a tool mounted on its one end and having magnotic poles installed at a fixed pitch along the direction of movement, magnetic pole teeth installed in opposition to each other and at a fixed pitch along the direction of movement in a longitudinal direction of the movable element, and a coil for exciting the magnetic pole teeth so that the adjacent magnetic pole teeth and opposed magnetic pole teeth act and different poles, respectively. The power tool further has a control circuit for reciprocating the movable element by exciting the coil, thereby to work on a workpiece by using the tool in the process of this reciprocating movement.

Power tool with a linear motor

A DC power source unit includes a main unit that generates DC voltage, and an output cable. The output cable is connected, either integrally or detachably, at one end to the output of the main unit and another end to an adapter plug. The adapter plug is electrically connected to an electrically powered tool, such as an electrical drill. An output voltage switching unit switches the level of voltage supplied by the main unit to the electrically powered tool, to a level that matches the rated voltage of the electrically powered tool that corresponds to the fitting portion of the adapter plug.

DC power source unit

A DC power source unit includes a main unit that generates DC voltage, and an output cable. The output cable has one end connected to the output of the main unit and another end attached to an adapter plug. The adapter plug Is electrically connected to an electrically powered tool, such as an electrical drill. Current flowing in the tool is detected every predetermined interval and accumulated electrical quantity is computed based on the detected current flowing in the tool. Based on the accumulated electrical quantity, the temperature of the tool is predicted. When it is determined that the tool is heated up to a first critical temperature based on the accumulated electrical quantity, an alarm unit is actuated. When it is determined that the tool is further heated up to a second critical temperature, supply of current to the tool is interrupted.

DC power source unit alarming before electrically powered tool is overheated and stopping power supply thereafter

A charging circuit generates a charging current from an ac supply which is supplied to a secondary battery in a battery package through first terminals. A second terminal receives a temperature detection signal from a thermistor on the secondary battery. A value of the temperature detection signal is sampled every predetermined interval. A memory stores the sampled value. A difference between the sampled value and the value from the memory is obtained, as well as the temperature decrease value between the sampled value and the value stored, when it applies. An error signal is generated when the difference is higher than a predetermined value and the operator is alarmed and informed of the error. The difference may be obtained between the sampled value and the value one-cycle-previously-sampled value from the memory, between the sampled value and a minimum of the sampled values, or between the sampled value and a charging start value of the sampled value. The thermistor is supplied with a supply voltage through a switch and an error condition caused by leakage of the electrolyte from the battery is detected when the voltage at the second terminal is higher than the predetermined value, the charging current generation circuit is controlled to stop generating the charging current.

Battery charging apparatus with error detection

Re-powering an electrical equipment after recovery of service interruption is prevented if the power switch of the electrical equipment stays in ON position. During a transit period of time just after recovery of service interruption, the detection voltage from a post-voltage detection circuit is set to exceed the detection voltage from a pre-voltage detection circuit. In this condition, a photo triac connected in series to the power switch is rendered non-conductive so that the electrical equipment will not be energized.

Device for preventing an electrical equipment from re-powering after

To discriminate that a rechargeable battery has reached an end of life, the maximum battery voltage detected during a preliminary charge time is compared with a predetermined reference voltage. When the comparison results indicate that the battery voltage is above the predetermined reference voltage, it is determined that the battery has reached the end of life.

Service-life discriminating feature added to a battery charger

A charge current to be supplied to a battery is selected depending on a remaining capacity of the battery to be charged and/or an initial temperature of the battery to be charged. A battery voltage or a battery temperature is being monitored and sampled at a relevant sampling interval determined depending on the selected charge current. A difference between two battery voltages or between two battery temperatures at two sampling points is sequentially computed and whether or not the battery has reached a fully charged condition is determined based on the computed results.

Battery charger monitoring battery voltage and/or temperature at

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

An automatic drilling machine has an electric drilling unit on which a cylindrical cutter is rotatably mounted. The drilling machine includes a drill motor for rotating the cutter and a feed motor for linearly moving the cutter for the purpose of drilling into materials such as concrete. The current flowing through the drill motor before a drilling load is imposed thereon is detected for a microprocessor to determine the type of the cutter being used. The drill motor is driven at a rotation speed suitable for the cutter being used and the feed motor is driven at a speed such that the rotation speed of the drill motor thus set is maintained unchanged. Particularly, the drill motor is driven at a reduced rotation speed from the start of drilling until a predetermined drilling depth is reached to reduce chatter vibration which may otherwise be generated if the drill motor is driven at a regular constant speed from the beginning of drilling until the end.

Dual-motor-driven drilling machine and method of controlling currents

A status of a battery is detected to determine whether an amount of residual charge is large or not. Detection of the status of the battery is performed on the basis of a change in the voltage level over a preliminary charge time. If the battery is determined to at low charge, then a sleep time is set. The full charge condition of the battery is, for example, detected when a second order differential of the voltage across the battery becomes negative. However, the computation of the second order differential is not performed during the sleep time. Further, to accurately determine the status of the battery, the duration of the preliminary charge time is prolonged if the battery is detected to have been deeply discharged.

Battery charger

To enable recharging of a battery under a low temperature circumstance, a rapid battery charger is provided with a rapid charge mode and a slow charge mode which are selectively used depending upon the temperature of the battery. The rapid charge mode is selected when the temperature is above a predetermined value, wherein the battery charger charges the battery with a charging current of more than 5 C, whereas the slow charge mode is selected when the temperature is below the predetermined value, wherein the battery charger charges the battery with a charging current of less than 1 C.

Rapid battery charger with slow charge mode at a low temperature

A management system for use in a centrifuge equipped with a detachable rotor which is rotatable so as to separate density-different samples by a centrifugal force due to the rotation. The management system is for managing the lifetime of the rotor on the basis of the detection results of an operated-condition detector for detecting operated conditions such as the number of times of rotation, running time and rotational speed of the rotor. The management system includes a data storing device which is provided on the rotor to be rotatable therewith and is composed of a magnetic recording medium to allow keeping data relating to the operated conditions of the rotor. Also included in the management system is a data processing unit coupled through a data reading and writing device such as a magnetic head to the data keeping device and also coupled to the operated-condition detector to be responsive to the operated conditions. The data processing unit reads out previous data from the data keeping device at the time of start of operation of the centrifuge, processes the operated conditions from the detector together with the read previous data to write on the data storing device new data produced by the data processing.

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Hitachinaka, Japan

Shigeru Shinohara