Abstract: In a battery pack which comprises: a battery set composed of two or more lithium battery cells connected in series; a first protection circuit including a first voltage detect part for detecting the voltage(s) of a part of the two or more battery cells, and a first signal output part for issuing an output signal when a detect voltage detected by the first voltage detect part goes below a given over-discharge judgment voltage value; a second protection circuit including a second voltage detect part for detecting the voltage(s) of another part of the two or more battery cells, and a second signal out part for issuing an output signal when the detect voltage of the battery cell detected by the second voltage detect part goes below a given over-discharge judgment voltage value; and, a switch which is connected to the current path of the battery set and can be turned on or off according to the output signals of the first and second signal output parts and, there is further provided dead time means connected betwee

Abstract: An electric grasscutter includes a motor (50) which drives a rotary blade (42). The motor (50) is a brushless motor accommodated in a motor housing (51) and including a rotor (53) provided integrally with an output shaft (52), and a stator (54) fixed to the motor housing (51). A motor control circuit which drives the motor (50) is accommodated in the motor housing (51). The motor control circuit includes an inverter having FETs (81-86) as switching elements, and a control section to control the FETs (81-86). The FETs (81-86) are fixed in contact with the motor housing (51).

Abstract: A motor has an output shaft which is rotatably supported by a housing, a rotor which is fixed to the output shaft and which comprises a printed-wiring board, and a stator which is fixed to the housing and which comprises a magnet facing the rotor. The printed-wiring board comprises a coil/commutator disk and a coil disk. A commutator conductor pattern is formed in a commutator region of the coil/commutator disk. Likewise, coil conductor patterns are formed in respective coil regions of the coil/commutator disk and of the coil disk.

Abstract: A power tool includes a body housing a motor and a power transmission mechanism positioned ahead of the motor for transmitting a power of the motor, a handle grip having an upper end portion connected to an approximately intermediate portion of the body and a lower end portion to which a battery is connected, a light emitting element positioned below the power transmission mechanism and receiving electrical power from the battery for illuminating a portion ahead of the body, and a trigger positioned below the power transmission mechanism for controlling a supply of the electrical power from the battery to the motor and to the light emitting element.

Abstract: An electrical power tool includes a motor, a load detecting unit, a trigger switch, and a power supplying unit. The load detecting unit detects a load applied to the motor. The trigger switch receives an instruction. The power supplying unit starts supplying of a driving electrical power to the motor when the trigger switch receives the instruction. The power supplying unit changes an amount of the driving electrical power based on the load detected by the load detecting unit.

Abstract: A miter saw including a base, a turntable, a support section extending from the turntable, and a circular saw unit supported to the support section. A rotation amount detection unit detects rotation amount of the turntable relative to the base. The turntable has a tilt support, and the support section has a tilting section supporting the circular saw unit and supported to the tilt support. A tilting amount detection unit detects tilting amount of the tilting section relative to the tilt support. The turntable has a microcomputer computing a rotation angle of the turntable and tilting angle of the circular saw unit, and a RAM storing the detected rotation amount and the tilting amount installed therein. A battery unit is provided in the turntable for supplying electrical power to electronic components including the rotation amount detection unit, the tilting amount detection unit, and the microcomputer.

Abstract: An impact tool (100) includes a spindle (11), a motor (1), a rotational impact system (10), a current detecting unit (32), and a current control unit (31). The spindle extends in an axial direction thereof. The motor provides the spindle with a rotational power in accordance with a motor current flowing therethrough. The rotational power rotates the spindle about the axis at an rpm value. The rotational impact system provides the spindle with an impact force in the axial direction, thereby transmitting both the rotational power and the impact force to an end bit. The current detecting unit detects a current value of the motor current. The current control unit reduces the current value if the current value detected by the current detecting unit exceeds a predetermined value.

Abstract: The controller determines the presence or absence of operation of the trigger switch according to an ON/OFF state of the main contact of the trigger switch and designating the rotation speed of the motor based on a signal outputted from the speed contact. The controller stops the rotation of the motor, after the trigger switch is activated and the main contact is turned ON and the motor is driven according to a signal outputted from the speed contact, when an OFF state of the main contact is detected, only in the case where a signal value outputted from the speed contact is a predetermined value or less.

Abstract: A compact battery pack with high handling ability and restraining degradation of battery cells. The battery pack includes an insertion portion to be inserted into a handle portion of a cordless power tool and an accommodation portion in which all battery cells are accommodatable. A protection board with a protection circuit that protects batteries against overcharge and over-discharge is installed in the insertion portion. A switching element is connected between the battery cells and a drive motor of the power tool. An air passage in communication with the battery pack is formed within the handle and a main housing of the cordless power tool. The switching element is positioned at the air passage.

Abstract: According to an aspect of the present invention, there is provided a power tool including: a brushless motor; switching elements that drive the brushless motor; a circuit board on which the switching elements are mounted; a transmission portion that transmits a driving force of the brushless motor; and a housing that houses the brushless motor, the switching elements, the circuit board and the transmission portion therein, wherein the switching elements include semiconductor elements each having terminals on a bottom surface thereof, and wherein the switching elements are surface mounted on the circuit board.

Abstract: According to an aspect of the invention, an oil pulse tool includes: a motor generating a driving force according to a driving voltage; an oil pulse unit driven by the driving force and generating a torque in a pulse-like shape when the motor passes a strike position on a shaft thereof; and an output shaft on which a front end tool is mounted, the output shaft being connected to the shaft, characterized in that the oil pulse tool further comprises driving adjusting means to control the driving voltage, the driving voltage is reduced during a given period including a timing when the torque is transmitted to the output shaft, and the reduced driving voltage is increased when the given period is finished.

Abstract: According to an aspect of the invention, an oil pulse tool includes: a motor generating a driving force; an oil pulse unit including a shaft, the oil pulse unit being driven by the motor and generating an impact torque on the shaft when the motor passes an impact position; and an output shaft on which a front end tool is attached, the output shaft being fixed to the shaft, wherein the oil pulse tool is provided with a rotational position detecting sensor of detecting a rotational position of the output shaft, and a torque detecting sensor of detecting generation of an impact torque, and the oil pulse tool is provided with detecting means for measuring a state required for reversely rotating the motor by generating an impact, and regularly rotating again the motor and passing a position of generating the impact, and detecting a reduction in a performance of the oil pulse unit by an aging change of the state.

Abstract: A charging voltage or an overcharge determination value for determining an overcharge state is set taking into consideration the states of secondary battery cells of a battery pack during charging. Charging of the secondary battery cells is then carried out using charging voltages set taking into consideration the states of the secondary battery cells. It is then determined whether or not the secondary battery cells are in an overcharged state using overcharge determination value is set taking into consideration the states of the secondary battery cells.

Abstract: A power tool includes a motor as a drive power source, a body housing the motor and having an end output unit for chucking an end tool, a handle grip connected to the body; and a light unit disposed to one of the handle grip and the body, and having a light-emitting element for providing illumination near the end tool. The light unit includes an angle adjuster and holder which adjusts and holds a lighting angle of the light-emitting element at least in accordance with a length of the end tool.

Abstract: An electric power tool includes a housing, a brushless motor, an output shaft, and a motor driver circuit. The housing defines an axial direction. The brushless motor is accommodated in the housing and having a drive shaft. The output shaft extends in a direction generally perpendicular to the drive shaft. The motor driver circuit is accommodated in the housing for driving the brushless motor. The housing has a cylindrical shape and has a part functioning as a grip portion.

Abstract: A compact battery pack with high handling ability and restraining degradation of battery cells. The battery pack includes an insertion portion to be inserted into a handle portion of a cordless power tool and an accommodation portion in which all battery cells are accommodatable. A protection board with a protection circuit that protects batteries against overcharge and over-discharge is installed in the insertion portion. A switching element is connected between the battery cells and a drive motor of the power tool. An air passage in communication with the battery pack is formed within the handle and a main housing of the cordless power tool. The switching element is positioned at the air passage.

Abstract: According to an aspect of the present invention, there is provided a power tool including: a motor; a switching device that switches over, in response to a conduction angle thereof, an AC voltage to be applied to the motor; a rotation speed setting unit that sets a target rotation speed of the motor; a rotation speed detection unit that detects an actual rotation speed of the motor; and a controller that determines the conduction angle by comparing the actual rotation speed with the target rotation speed and that controls the switching device by use of the conduction angle based on a maximum conduction angle, the maximum conduction angle being set in accordance with the target rotation speed.

Abstract: Abnormal detecting means 112 for detecting that an electrically conductive foreign substance has migrated into a charging device 1 is provided, and whether or the foreign substance has migrated is judged from the detection result of the abnormal detecting means 112.

Abstract: A battery pack includes a plurality of lithium battery cells, an analog thermo sensing member, and an analog switch. The analog thermo sensing member detects, in an analog form, a battery temperature of at least one of the plurality of lithium battery cells, and outputs an output preventing signal if the battery temperature is over a first predetermined temperature. The analog switch element is the plurality of lithium battery cells in series, and is switched, based on the output preventing signal, to a state in which a current is prevented from flowing in the plurality of lithium battery cells.

Abstract: A power tool includes a motor as a drive power source, a body housing the motor and having an end output unit for chucking an end tool, a handle grip connected to the body; and a light unit disposed to one of the handle grip and the body, and having a light-emitting element for providing illumination near the end tool. The light unit comprises switch means for switching the light-emitting element on and off, and an off circuit for automatically turning the light-emitting element off at a predetermined time after the light-emitting element turns on.