Patents by Inventor Kazutaka Iwata

Kazutaka Iwata has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 9114519
    Abstract: A current detection circuit (18) detects that a drive current of the stator coil (2d) is exceeding a threshold value Ir. A rotation number detection circuit (17) detects that the number of rotations of a rotor (2a) is lower than a threshold value Nr. A computing part (20) outputs a PWM signal which switches a semiconductor switching element (3a) of the inverter circuit part (3). The computing part (20) changes the threshold values Ir and Nr in accordance with the PWM duty of the PWM signal determined in accordance with a pressed distance of a switch trigger (7) and detects a locked state of the motor (2) on the conditions that the motor current I is exceeding the set threshold value Ir and that the number of rotations N thereof is lower than the threshold value Nr.
    Type: Grant
    Filed: February 16, 2009
    Date of Patent: August 25, 2015
    Assignee: HITACHI KOKI CO., LTD.
    Inventors: Kazutaka Iwata, Kenichirou Yoshida, Shinji Watanabe
  • Publication number: 20150222212
    Abstract: An electric power tool comprising a voltage conversion circuit configured to control magnitude of a voltage applied to a motor in accordance with magnitude of load.
    Type: Application
    Filed: September 27, 2013
    Publication date: August 6, 2015
    Applicant: HITACHI KOKI CO., LTD.
    Inventor: Kazutaka Iwata
  • Patent number: 9048699
    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.
    Type: Grant
    Filed: May 20, 2009
    Date of Patent: June 2, 2015
    Assignee: HITACHI KOKI CO., LTD.
    Inventors: Katsuhiro Oomori, Junichi Toukairin, Nobuhiro Takano, Kazutaka Iwata, Tomomasa Nishikawa
  • Publication number: 20150047866
    Abstract: An electric tool in which a pulsating input voltage is configured to be supplied to a drive circuit of a motor, the electric tool including: a rotation speed detection unit configured to detect a rotation speed of the motor, characterized in that the electric tool further includes: a control part configured to vary a determining value for determining whether the rotation speed of the motor satisfies a predetermined condition or not, so as to be synchronous with a pulsation cycle of the input voltage supplied to the drive circuit.
    Type: Application
    Filed: March 29, 2013
    Publication date: February 19, 2015
    Applicant: HITACHI KOKI CO., LTD.
    Inventors: Hironori Sakai, Naoki Tadokoro, Kazutaka Iwata
  • Publication number: 20150042246
    Abstract: An electric tool in which a pulsating input voltage is inputted to a drive circuit of a motor, characterized in that the electric tool includes: a control part configured to vary output power or output voltage supplied to the motor from the drive circuit in accordance with the pulsation of the input voltage inputted to the drive circuit.
    Type: Application
    Filed: March 29, 2013
    Publication date: February 12, 2015
    Inventors: Naoki Tadokoro, Kazutaka Iwata
  • Patent number: 8931576
    Abstract: A power tool has a motor, a power supply unit, a trigger unit, a control unit, and a motor load detection unit. The power supply unit supplies power to the motor. The trigger unit causes the power supply unit to start applying a voltage to the motor. The control unit controls the power supply unit to increase the voltage to the motor at a constant increasing rate. The motor load detection unit detects a motor load. The control unit changes the constant increasing rate in accordance with the motor load.
    Type: Grant
    Filed: May 17, 2011
    Date of Patent: January 13, 2015
    Assignee: Hitachi Koki., Ltd.
    Inventor: Kazutaka Iwata
  • Patent number: 8925645
    Abstract: An oil pulse tool includes a motor, an oil pulse unit, an output shaft on which a front end tool is attached, a torque detecting sensor for detecting generation of an impact torque, and an operating portion configured to detect a time period between a first impact torque detected by the torque detecting sensor and a second impact torque detected by the torque detecting sensor. The second impact torque is smaller than the first impact torque. The operating portion carries out a notification when the time period between the first impact torque and the second impact torque is less than a predetermined evaluation value for the time period between the first impact torque and the second impact torque.
    Type: Grant
    Filed: May 8, 2009
    Date of Patent: January 6, 2015
    Assignee: Hitachi Koki Co., Ltd.
    Inventors: Tetsuhiro Harada, Tomomasa Nishikawa, Kazutaka Iwata, Shinki Ohtsu, Nobuhiro Takano
  • Publication number: 20140151080
    Abstract: A drilling tool 1 includes: an attaching portion 15 to which a tip tool is attached; and a housing for holding the attaching portion 15. An inclination sensor 16A for detecting inclination of the drilling tool 1 and an electronic substrate 16B supporting the inclination sensor 16A, which converts a result of the detection of the inclination sensor 16A into an electric signal, are provided inside the housing. A weight 16D is provided in the electronic substrate 16B. Oscillation generated in operation of the drilling tool 1 and transmitted to the inclination sensor 16A is reduced by the weight.
    Type: Application
    Filed: August 13, 2012
    Publication date: June 5, 2014
    Applicant: HITACHI KOKI CO., LTD.
    Inventors: Satoshi Abe, Ookubo Takahiro, Kazutaka Iwata
  • Publication number: 20140116737
    Abstract: A casing of a hedge clipper which is a portable tool is provided with a power source housing in which an electric motor is housed and a main handle held by a worker, and blades serving as a tip tool are provided to the casing. An operation display panel is provided on the main handle, and a driving information display unit which displays a battery remaining capacity and a rotation speed of an electric motor as a plurality of pieces of driving information is provided on the operation display panel. The selection of the information to be displayed is switched by the operation of an operation switch unit provided in the operation display panel.
    Type: Application
    Filed: October 31, 2013
    Publication date: May 1, 2014
    Applicant: Hitachi Koki Co., Ltd.
    Inventors: Kazutaka IWATA, Yasutaka SHIMIZU, Shogo SHIBATA
  • Patent number: 8640789
    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.
    Type: Grant
    Filed: May 8, 2009
    Date of Patent: February 4, 2014
    Assignee: Hitachi Koki Co., Ltd.
    Inventors: Tetsuhiro Harada, Tomomasa Nishikawa, Kazutaka Iwata, Shiniki Otsu, Nobuhiro Takano
  • Publication number: 20140015350
    Abstract: A power tool includes a housing, a brushless motor, and a cover member. The housing has an air intake hole and an air exhaust hole formed therein, the housing having an inner surface. The brushless motor has an outer surface disposed in the housing, a first endface near the air intake hole, and a second endface near the air exhaust hole. The cover member covers at least one of the first endface and the second endface for preventing dust from entering the brushless motor. The inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole.
    Type: Application
    Filed: September 20, 2013
    Publication date: January 16, 2014
    Applicant: Hitachi KoKi Co., Ltd.
    Inventors: Kenichirou Yoshida, Katsuhiro Oomori, Yoshihiro Komuro, Kazutaka Iwata
  • Publication number: 20140001993
    Abstract: An electric power tool includes: a brushless motor having a plurality of stator windings and configured to rotate in accordance with voltages applied to the plurality of stator windings, an induced voltage being generated in accordance with a rotation of the brushless motor; a rectifier circuit configured to rectify an AC voltage; a smoothing capacitor configured to smooth the AC voltage rectified by the rectifier circuit to a pulsation voltage having a maximum value larger than the induced voltage and a minimum value smaller than the induced voltage; and an inverter circuit configured to perform switching operations to output the pulsation voltage to the plurality of stator windings by rotation.
    Type: Application
    Filed: March 19, 2012
    Publication date: January 2, 2014
    Applicant: Hitachi Koki Co., Ltd.
    Inventors: Kazutaka Iwata, Toshiaki Koizumi
  • Publication number: 20130333910
    Abstract: According to one embodiment, an impact tool includes: a motor; and a hammer that is connected to the motor and that has a striking-side surface; and an anvil that is journalled to be rotatable with respect to the hammer, that has a struck-side surface and that provides a striking power to a tip tool, wherein the motor is drivable in: a first driving mode in which the motor is continuously driven in a normal rotation; a second driving mode in which the motor is intermittently driven only in the normal rotation; and a third driving mode in which the motor is intermittently driven in the normal rotation and in a reverse rotation.
    Type: Application
    Filed: July 29, 2010
    Publication date: December 19, 2013
    Applicant: HITACHI KOKI CO., LTD.,
    Inventors: Hideyuki Tanimoto, Nobuhiro Takano, Tomomasa Nishikawa, Kazutaka Iwata, Hironori Mashiko, Hayato Yamaguchi, Atsushi Nakagawa, Katsuhiro Oomori, Mizuho Nakamura, Hiroki Uchida, Saroma Nakano
  • Patent number: 8607892
    Abstract: According to an aspect of the present invention, there is provided a rotary striking tool includes: a motor; an oil pulse unit that is driven by the motor; an output shaft that is coupled to the oil pulse unit so that a tip tool can be attached to the output shaft; a first detection unit that detects a rotation angle of the motor and outputs a first output signal; a second detection unit that detects an impact generated at the oil pulse unit and outputs a second output signal; and a control unit that controls a rotation of the motor, wherein the control unit uses a portion of the second output signal based on the first output signal for control of the rotation of the motor.
    Type: Grant
    Filed: September 8, 2010
    Date of Patent: December 17, 2013
    Assignee: Hitachi Koki Co., Ltd.
    Inventors: Yoshio Iimura, Kenro Ishimaru, Kazutaka Iwata, Nobuhiro Takano
  • Patent number: 8541913
    Abstract: A power tool includes a housing, a brushless motor, and a cover member. The housing has an air intake hole and an air exhaust hole formed therein, the housing having an inner surface. The brushless motor has an outer surface disposed in the housing, a first endface near the air intake hole, and a second endface near the air exhaust hole. The cover member covers at least one of the first endface and the second endface for preventing dust from entering the brushless motor. The inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole.
    Type: Grant
    Filed: April 13, 2012
    Date of Patent: September 24, 2013
    Assignee: Hitachi Koki Co., Ltd.
    Inventors: Kenichirou Yoshida, Katsuhiro Oomori, Yoshihiro Komuro, Kazutaka Iwata
  • Publication number: 20130189041
    Abstract: A power tool includes: a motor driving an end bit; a housing accommodating the motor; a distance measuring sensor provided at the housing; and a controlling section connected to the distance measuring sensor. The controlling section is configured to exclude an abnormal value from measurement value measured by the distance measuring sensor.
    Type: Application
    Filed: September 13, 2011
    Publication date: July 25, 2013
    Applicant: Hitachi Koki Co., Ltd.
    Inventors: Satoshi Abe, Takahiro Okubo, Kazutaka Iwata
  • Publication number: 20130186661
    Abstract: A power tool including: a housing configured to support an end bit, a motor accommodated in the housing, a transmission mechanism, a trigger switch, a load judging unit, and a motor stop control unit. The transmission mechanism transmits a rotational force of the motor to the end bit. The trigger switch is configured to switch between instructions to the motor. The instructions include a rotation instruction for providing a rotation state of the motor and a stopping instruction for providing a stopping state of the motor. The load judging unit judges whether or not a load is applied to the end bit during rotation of the motor. The motor stop control unit stops the rotation of the motor irrespective of the instructions of the trigger switch when the load judging unit judges that no load is applied to the end bit and a period of a non-load state exceeds a predetermined time period.
    Type: Application
    Filed: September 13, 2011
    Publication date: July 25, 2013
    Applicant: Hitachi Koki Co., Ltd.
    Inventors: Takahiro Okubo, Kazutaka Iwata
  • Publication number: 20130025892
    Abstract: An electronic pulse driver includes a motor, a hammer, an anvil, an end tool mounting unit, a power supply unit, a temperature detecting unit, and a controller. The hammer is drivingly rotatable in forward and reverse directions by the motor. The anvil is provided separately from the hammer and rotated upon striking of the hammer. The power supply unit alternately supplies a forward electric power and a reverse electric power to the motor in a first cycle. The temperature detecting unit is configured to detect a temperature of the motor. The controller is configured to control the power supply unit to alternately supplies the forward electric power and the reverse electric power in a second cycle longer than the first cycle when the temperature of the motor detected by the temperature detecting unit increases to a prescribed value.
    Type: Application
    Filed: March 11, 2011
    Publication date: January 31, 2013
    Applicant: HITACHI KOKI CO., LTD.
    Inventors: Hironori Mashiko, Nobuhiro Takano, Kazutaka Iwata, Tomomasa Nishikawa, Katsuhiro Oomori, Mizuho Nakamura, Yutaka Ito
  • Publication number: 20130028674
    Abstract: A drilling device drilling to a desired depth without a gauge. The drilling device includes a distance sensor positioned on an imaginary line spanning between a front end of the housing and a hand gripped portion. The distance sensor is away form a front end of a gear housing by a distance Ls. The distance sensor provides an effective measurement range. The relationship of L1?Ls and Ls+Lb?L2 is satisfied where L1 represents a distance between the distance sensor and a point closest to the distance sensor and defining a lower limit of the effective measurement range, L2 represents a distance between the distance sensor and a point farthest from the distance sensor and defining an upper limit of the effective measurement range, and Lb represents a distance between the front end of the housing and a tip end of the end bit.
    Type: Application
    Filed: April 12, 2011
    Publication date: January 31, 2013
    Applicant: Hitachi KoKi Co., Ltd.
    Inventors: Takahiro Okubo, Satoshi Abe, Kazutaka Iwata
  • Patent number: 8360166
    Abstract: According to an aspect of the present invention, there is provided a rotary striking tool, including: a motor; an impact unit having a driving part being driven by the motor and an output part; a tip-tool side output shaft that is coupled to the output part; an impact detection unit that detects an impact generated at the impact unit; and a control unit programmed to: control the impact unit to perform a confirmation striking when the impact detected by the impact detection unit reaches a prescribed value, detect a rotation angle of the output shaft at the confirmation striking, determine whether a fastening operation is completed when the detected rotation angle is equal to or smaller than a predetermined angle, and continue the fastening operation when the detected rotation angle is larger than the predetermined angle.
    Type: Grant
    Filed: September 8, 2010
    Date of Patent: January 29, 2013
    Assignee: Hitachi Koki Co., Ltd.
    Inventors: Yoshio Iimura, Kenro Ishimaru, Kazutaka Iwata, Nobuhiro Takano