Abstract: An improved hand-held power tool is provided which can effectively reduce whirling vibration caused by imbalance of a rotating element. The power tool has a grip that is connected to a tool body and designed to be held by a user and a self-synchronous mechanism that reduces whirling vibration caused in the tool body or the grip when the tool bit is driven. The self-synchronous mechanism is of a phase variable type, having a rotating body which serves as a vibrator and is rotationally driven by a driving source different from a driving source for the tool bit. The self-synchronous mechanism is disposed in the tool body or the grip in which whirling vibration is caused, and arranged such that a phase of vibration of the rotating body is automatically tuned to a phase of the whirling vibration, thereby reducing the whirling vibration.

Abstract: A rotary impact tool includes: a hammer rotating by receiving a rotational force of a motor; an anvil rotating by receiving a rotational force of the hammer; and an end tool attached to the anvil, the rotary impact tool being constructed such that when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle, the rotary impact tool including an impact detector configured to detect impacts and a speed switching device configured to switch the rotational speed of the motor, and when the impact detector detects an impact during rotation of the anvil in a tightening direction, the speed switching device switches the rotational speed of the motor from a normal speed to a low speed.

Abstract: A power tool of the present teachings comprises a prime mover that drives a tool, a main switch that causes the prime mover to operate when the main switch is turned on and causes the prime mover to stop operating when the main switch is turned off, an illuminator that lights a working area of the tool, and a lighting mode selector switch for switching the lighting mode of the illuminator between a plurality of lighting modes which include a first lighting mode and a second lighting mode. When the first lighting mode is selected, the illuminator will be turned on for a first predetermined period from the point at which the main switch is turned off. When the second lighting mode is selected, the illuminator will not be turned on during the first predetermined period from the point at which the main switch is turned off.

Abstract: The present application discloses an apparatus including: a motor model that reflects a characteristic of a motor and includes at least inputs pertaining to a first quantity of state and a second quantity of state and an output pertaining to a third quantity of state; a comparator that calculates a difference between the third quantity of state in an actual motor and the third quantity of state output from the motor model; and an amplifier that amplifies an output of the comparator at a predetermined gain. The first quantity of state in the actual motor is input into the motor model as the first quantity of state, and an output of the amplifier is input into the motor model as the second quantity of state. The apparatus then uses the output of the amplifier as an estimated value of the second quantity of state in the actual motor.

Abstract: A motor controller is provided with a first PWM circuit that repeatedly outputs an on-signal at a first carrier frequency, a second PWM circuit that repeatedly outputs an on-signal at a second carrier frequency that is lower than the first carrier frequency, an AND circuit that receives both the on-signal outputted from the first PWM circuit and the on-signal outputted from the second PWM circuit and outputs a third on-signal which is a logical product of the received on-signals, and a voltage apply circuit that applies a voltage to the motor intermittently in synchronization with the third on-signal outputted from the AND circuit. At least one of the first carrier frequency and the second carrier frequency is equal to or lower than 1 kHz or equal to or higher than 3 kHz. As a result, generation of an unpleasant noise by a motor controller using two PWM circuits may be suppressed.

Abstract: A motor controller is provided with a velocity processing unit that determines a corrected target rotation velocity by correcting the inputted target rotation velocity of the motor in accordance with a velocity deviation between the inputted target rotation velocity and an actual rotation velocity detected from the motor, a first PWM circuit that repeatedly outputs an on-signal having a first pulse width at a first carrier frequency, wherein the first pulse width of the on-signal is modulated by the first PWM circuit in accordance with the corrected target rotation velocity, a second PWM circuit that repeatedly outputs an on-signal having a second pulse width at a second carrier frequency, wherein the second pulse width is different from the first pulse width, the second carrier frequency is lower than the first carrier frequency, and the second pulse width of the on-signal is modulated by the second PWM circuit in accordance with the corrected target rotation velocity, an AND circuit that receives the on-sig

Abstract: An improved hand-held power tool is provided which can effectively reduce whirling vibration caused by imbalance of a rotating element. The power tool has a grip that is connected to a tool body and designed to be held by a user and a self-synchronous mechanism that reduces whirling vibration caused in the tool body or the grip when the tool bit is driven. The self-synchronous mechanism is of a phase variable type, having a rotating body which serves as a vibrator and is rotationally driven by a driving source different from a driving source for the tool bit. The self-synchronous mechanism is disposed in the tool body or the grip in which whirling vibration is caused, and arranged such that a phase of vibration of the rotating body is automatically tuned to a phase of the whirling vibration, thereby reducing the whirling vibration.

Abstract: An electric power tool includes a direct current motor, at least one switching device, a trigger switch, a control unit, and a drive unit. The control unit sets a driving duty ratio for PWM controlling the direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when an operation of the trigger switch is started until when a predetermined start-up time has elapsed.

Abstract: A rotary impact tool includes: a hammer rotating by receiving a rotational force of a motor; an anvil rotating by receiving a rotational force of the hammer; and an end tool attached to the anvil, the rotary impact tool being constructed such that when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle, the rotary impact tool including an impact detection means detecting impacts and a speed switching means switching the rotational speed of the motor, and when the impact detection means detects an impact during rotation of the anvil in a tightening direction, the speed switching means switches the rotational speed of the motor from a normal speed to a low speed.

Abstract: A motor controller is provided with a velocity processing unit that determines a corrected target rotation velocity by correcting the inputted target rotation velocity of the motor in accordance with a velocity deviation between the inputted target rotation velocity and an actual rotation velocity detected from the motor, a first PWM circuit that repeatedly outputs an on-signal having a first pulse width at a first carrier frequency, wherein the first pulse width of the on-signal is modulated by the first PWM circuit in accordance with the corrected target rotation velocity, a second PWM circuit that repeatedly outputs an on-signal having a second pulse width at a second carrier frequency, wherein the second pulse width is different from the first pulse width, the second carrier frequency is lower than the first carrier frequency, and the second pulse width of the on-signal is modulated by the second PWM circuit in accordance with the corrected target rotation velocity, an AND circuit that receives the on-sig

Abstract: A motor controller is provided with a first PWM circuit that repeatedly outputs an on-signal at a first carrier frequency, a second PWM circuit that repeatedly outputs an on-signal at a second carrier frequency that is lower than the first carrier frequency, an AND circuit that receives both the on-signal outputted from the first PWM circuit and the on-signal outputted from the second PWM circuit and outputs a third on-signal which is a logical product of the received on-signals, and a voltage apply circuit that applies a voltage to the motor intermittently in synchronization with the third on-signal outputted from the AND circuit. At least one of the first carrier frequency and the second carrier frequency is equal to or lower than 1 kHz or equal to or higher than 3 kHz. As a result, generation of an unpleasant noise by a motor controller using two PWM circuits may be suppressed.

Abstract: A power tool of the present teachings comprises a prime mover that drives a tool, a main switch that causes the prime mover to operate when the main switch is turned on and causes the prime mover to stop operating when the main switch is turned off, an illuminator that lights a working area of the tool, and a lighting mode selector switch for switching the lighting mode of the illuminator between a plurality of lighting modes which include a first lighting mode and a second lighting mode. When the first lighting mode is selected, the illuminator will be turned on for a first predetermined period from the point at which the main switch is turned off. When the second lighting mode is selected, the illuminator will not be turned on during the first predetermined period from the point at which the main switch is turned off.

Abstract: An electric power tool includes a direct current motor, at least one switching device, a trigger switch, a control unit, and a drive unit. The control unit sets a driving duty ratio for PWM controlling the direct current motor so as to increase the driving duty ratio in a stepwise manner in accordance with an operation continuation time of the trigger switch during a period from when an operation of the trigger switch is started until when a predetermined start-up time has elapsed.

Abstract: It is an object of the present invention to provide a technique to increase efficiency of the output torque of the blushless motor to drive a power tool. A representative power tool may comprise a tool bit, a brushless motor to drive the tool bit, a battery to operate the brushless motor and a control device. The control device may operate the brushless motor by means of the battery. The control device may include an advance angle controlling section to control an advance angle of the brushless motor. According to the present teachings, the advance angle of the brushless motor may be determined based upon indexes that reflect working condition of the tool bit when the brushless motor is under the operation. By reflecting the working condition of the tool bit to the determination of the advance angle of the brushless motor, the brushless motor can be operated with higher efficiency under the various working condition such as a hard joint operation and a soft joint operation.

Abstract: It is an object of the invention to provide a technique to effectively prevent a power tool from being adversely affected when a battery is removed from the power tool. According to the present invention, a power tool is provided that includes a tool bit, a motor that drives the tool bit, a body that houses the motor, a battery detachably coupled to the body so as to supply driving current to operate the motor, a control device that controls the operation of the motor and a power circuit that leads the driving current from the battery to the motor. Within the power tool, the control device stops the motor prior to an interruption of the power circuit when the battery is disengaged from the body in order to prevent a large driving current from being passed through the power circuit. As a result, arc can be effectively prevented from being generated between the battery and the body of the power tool.

Abstract: It is an object of the present invention to provide a technique to increase efficiency of the output torque of the blushless motor to drive a power tool. A representative power tool may comprise a tool bit, a brushless motor to drive the tool bit, a battery to operate the brushless motor and a control device. The control device may operate the brushless motor by means of the battery. The control device may include an advance angle controlling section to control an advance angle of the brushless motor. According to the present teachings, the advance angle of the brushless motor may be determined based upon indexes that reflect working condition of the tool bit when the brushless motor is under the operation. By reflecting the working condition of the tool bit to the determination of the advance angle of the brushless motor, the brushless motor can be operated with higher efficiency under the various working condition such as a hard joint operation and a soft joint operation.

Abstract: It is an object of the invention to provide a technique to effectively prevent a power tool from being adversely affected when a battery is removed from the power tool. According to the present invention, a power tool is provided that includes a tool bit, a motor that drives the tool bit, a body that houses the motor, a battery detachably coupled to the body so as to supply driving current to operate the motor, and a battery removal preventing device. Within the power tool, the battery removal preventing device prevents the battery from being removed from the body during operation of the motor and allows the battery to be removed from the body only when the motor is stopped. As a result, arc can be effectively prevented from being generated between the battery and the body of the power tool.

Abstract: It is an object of the present teachings to provide a technique that rationalizes the structure of the brushless motor so as to save space in the power tool. According to the present teachings, a representative brushless motor utilized in a power tool may comprise a stator, a rotor and a cooling fan. The brushless motor is disposed within the power tool. The brushless motor is adapted to supply driving current to the stator to drive a tool bit of the power tool by rotating the rotor. The cooling fan is molded of a magnetic or conductive material so that the cooling fan also serves as a rotating position detector that detects the rotating position of the rotor with respect to the stator. Because the cooling fan may also have a function of rotating position detector of the rotor, the inner space of the power tool can be rationalized.

Abstract: It is an object of the present teachings to provide a technique that rationalizes the structure of the brushless motor so as to save space in the power tool. According to the present teachings, a representative brushless motor utilized in a power tool may comprise a stator, a rotor and a cooling fan. The brushless motor is disposed within the power tool. The brushless motor is adapted to supply driving current to the stator to drive a tool bit of the power tool by rotating the rotor. The cooling fan is molded of a magnetic or conductive material so that the cooling fan also serves as a rotating position detector that detects the rotating position of the rotor with respect to the stator. Because the cooling fan may also have a function of rotating position detector of the rotor, the inner space of the power tool can be rationalized.

Abstract: It is an object of the invention to provide a technique to effectively prevent a power tool from being adversely affected when a battery is removed from the power tool. According to the present invention, a power tool is provided that includes a tool bit, a motor that drives the tool bit, a body that houses the motor, a battery detachably coupled to the body so as to supply driving current to operate the motor, and a battery removal preventing device. Within the power tool, the battery removal preventing device prevents the battery from being removed from the body during operation of the motor and allows the battery to be removed from the body only when the motor is stopped. As a result, arc can be effectively prevented from being generated between the battery and the body of the power tool.