Patents by Inventor Kazuo Tahara

Kazuo Tahara 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: 7759837
    Abstract: Stator claw poles are disposed at a stator core at a position facing opposite a rotor so as to alternately range from the two sides along the axial direction. With a plurality of magnetic poles thus formed, the distance by which the gap between the front end portions of the stator claw poles and the stator outer circumference ranges is increased, which, in turn, reduces the reactance guided to a stator coil. It is ensured that the magnetic reluctance manifesting between the front end portions of the stator claw poles and an enclosing member that holds the stator core, facing opposite the centers of the claw poles along the circumferential direction, is greater than the magnetic reluctance manifesting between the front portions and the stator core enclosing member facing opposite the front end portions.
    Type: Grant
    Filed: June 18, 2008
    Date of Patent: July 20, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Toshio Ishikawa, Minoru Yabuki, Yoshihisa Ishikawa, Kazuo Tahara
  • Publication number: 20080315700
    Abstract: Stator claw poles are disposed at a stator core at a position facing opposite a rotor so as to alternately range from the two sides along the axial direction. With a plurality of magnetic poles thus formed, the distance by which the gap between the front end portions of the stator claw poles and the stator outer circumference ranges is increased, which, in turn, reduces the reactance guided to a stator coil. It is ensured that the magnetic reluctance manifesting between the front end portions of the stator claw poles and an enclosing member that holds the stator core, facing opposite the centers of the claw poles along the circumferential direction, is greater than the magnetic reluctance manifesting between the front portions and the stator core enclosing member facing opposite the front end portions.
    Type: Application
    Filed: June 18, 2008
    Publication date: December 25, 2008
    Applicant: Hitachi, Ltd.
    Inventors: Toshio Ishikawa, Minoru Yabuki, Yoshihisa Ishikawa, Kazuo Tahara
  • Patent number: 7395888
    Abstract: A vehicle drive device comprises an actuator located between an electric motor and axles for driving the vehicle, a built-in power source for supplying electric power to the actuator, and a control means for controlling the drive of the actuator. The built-in power source can be consisted of a battery, and the actuator can be consisted of an electromagnetic clutch. Here, the vehicle drive device further comprises a boost means, such as a DC-DC converter, for boosting voltage of the built-in power source such as the battery. The output voltage of the boost means is supplied electric power to the actuator such as the electromagnetic clutch. The output voltage of the boost means can be also supplied the electric power to the field coil of the electric motor.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: July 8, 2008
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Daisuke Yamamoto, Kazuo Tahara
  • Patent number: 7279855
    Abstract: A vehicle electric drive system and a hybrid engine-motor type vehicle drive system realizing simplification and miniaturization of electric parts and, moreover, reduction in cost while maintaining performances can be provided. A part 1 of wheels is driven by an engine. The wheels are driven by a motor as necessary. The motor, a generator, and an accessory battery are connected to each other via a voltage step-up/step-down device. The voltage step-up/step-down device has a function of stepping up power of the battery and supplying the stepping up power to the motor, and a function of stepped down power of the generator and supplying the stepped down power to the battery and the accessories.
    Type: Grant
    Filed: April 2, 2004
    Date of Patent: October 9, 2007
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Kazuo Tahara, Keisuke Nishidate, Kenichi Yoshida, Hisaya Shimizu, Toshiyuki Innami, Shinichi Fujino
  • Publication number: 20060202582
    Abstract: A synchronous motor with low vibrations and an electric driving system using the motor. A field-coil synchronous motor comprises a stator and a rotor rotatably supported at the inner peripheral side of the stator with a gap left relative to the stator. The stator has a stator coil supplied with electric power while being controlled such that driving torque is reduced as a rotation speed of the rotor increases, and the rotor has a field coil supplied with a field current while being controlled such that the field current is reduced as the rotation speed of the rotor increases. The rotor is a tandem claw-pole rotor comprising plural pairs of N- and S-claw poles disposed side by side in an axial direction, and the plural pairs of claw poles of said tandem claw-pole rotor are relatively shifted from each other in a circumferential direction.
    Type: Application
    Filed: February 10, 2006
    Publication date: September 14, 2006
    Applicant: Hitachi, Ltd.
    Inventors: Yosuke Umesaki, Takashi Kobayashi, Kenichi Yoshida, Keisuke Nishidate, Kazuo Tahara
  • Publication number: 20060152180
    Abstract: A vehicle electric drive system and a hybrid engine-motor type vehicle drive system realizing simplification and miniaturization of electric parts and, moreover, reduction in cost while maintaining performances can be provided. A part 1 of wheels is driven by an engine. The wheels are driven by a motor as necessary. The motor, a generator, and an accessory battery are connected to each other via a voltage step-up/step-down device. The voltage step-up/step-down device has a function of stepping up power of the battery and supplying the stepping up power to the motor, and a function of stepped down power of the generator and supplying the stepped down power to the battery and the accessories.
    Type: Application
    Filed: April 2, 2004
    Publication date: July 13, 2006
    Inventors: Kazuo Tahara, Keisuke Nishidate, Kenichi Yoshida, Hisaya Shimizu, Toshiyuki Innami, Shinichi Fujino
  • Patent number: 7057327
    Abstract: A vehicular alternator is provided which can effectively utilize the magnetic flux of a permanent magnet disposed between claw-type magnetic poles and can improve an output of the alternator. The vehicular alternator comprises a rotor and a stator constituted by coiling stator windings over a stator core, the rotor comprising a pair of claw-type magnetic poles arranged in an opposed relation, a permanent magnet disposed between adjacent two of a plurality of claws provided on the pair of claw-type magnetic poles, and field windings coiled radially inward of the plurality of claws. Each of the plurality of claws of the rotor is formed to have a shape coming into contact with the whole of a magnetic pole surface of the permanent magnet.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: June 6, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Kanazawa, Kenji Miyata, Kaoru Kawabata, Kohji Maki, Kazuo Tahara, Susumu Sasaki, Ryoichi Takahata
  • Patent number: 6938713
    Abstract: The present invention is characterized by a hybrid car comprising a motor generator mechanically connected with the crank shaft of an internal combustion engine for driving a car wherein the internal combustion engine is started by electric power supplied by a battery and power is generated by rotation from the internal combustion engine to charge the battery, an inverter for controlling the drive and power generation of the motor generator, and a control circuit for controlling the inverter, this hybrid car further characterized in that the motor generator is driven by battery power to start the internal combustion engine, and after the internal combustion engine has started, the battery is charged by the generator mode operation of the motor generator using the power of the internal combustion engine, wherein a step-down chopper circuit is provided between the battery and the inverter, and step-down control is provided to ensure that the power generation voltage will reach the level of the battery charging
    Type: Grant
    Filed: September 20, 1999
    Date of Patent: September 6, 2005
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Kazuo Tahara, Houng Joong Kim, Tsunehiro Endo, Ryoso Masaki, Kou Ajima, Toshiyuki Innami, Keiichi Mashino, Yoshimi Sakurai
  • Publication number: 20050190524
    Abstract: A vehicle drive device comprises an actuator located between an electric motor and axles for driving the vehicle, a built-in power source for supplying electric power to the actuator, and a control means for controlling the drive of the actuator. The built-in power source can be consisted of a battery, and the actuator can be consisted of an electromagnetic clutch. Here, the vehicle drive device further comprises a boost means, such as a DC-DC converter, for boosting voltage of the built-in power source such as the battery. The output voltage of the boost means is supplied electric power to the actuator such as the electromagnetic clutch. The output voltage of the boost means can be also supplied the electric power to the field coil of the electric motor.
    Type: Application
    Filed: February 25, 2005
    Publication date: September 1, 2005
    Applicants: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Daisuke Yamamoto, Kazuo Tahara
  • Patent number: 6833646
    Abstract: A hybrid drive type vehicle having a permanent magnet type synchronous motor can provide high torque characteristics in low revolution speed range of the engine and high power generation characteristics at high revolution speed range of the engine. The hybrid drive type vehicle includes an electric rotary machine being formed with a stator and a rotor. A field magnet of the rotor include a first field magnet and a second field magnet. The first and second field magnets are opposing with a magnetic pole of the stator and having a mechanism for varying a phase of a magnetic pole resulting from combination of the first and second field magnets relative to the magnetic pole of the first field magnet depending upon direction of a torque of the rotor.
    Type: Grant
    Filed: January 8, 2004
    Date of Patent: December 21, 2004
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Kim Houng Joong, Kazuo Tahara, Kou Ajima, Koki Ueta, Toshiyuki Innami, Noriaki Hino, Taizo Miyazaki, Tomoyuki Hanyu, Kousaku Ohno
  • Publication number: 20040189128
    Abstract: A hybrid drive type vehicle having a permanent magnet type synchronous motor can provide high torque characteristics in low revolution speed range of the engine and high power generation characteristics at high revolution speed range of the engine. The hybrid drive type vehicle includes an electric rotary machine being formed with a stator and a rotor. A field magnet of the rotor include a first field magnet and a second field magnet. The first and second field magnets are opposing with a magnetic pole of the stator and having a mechanism for varying a phase of a magnetic pole resulting from combination of the first and second field magnets relative to the magnetic pole of the first field magnet depending upon direction of a torque of the rotor.
    Type: Application
    Filed: January 8, 2004
    Publication date: September 30, 2004
    Inventors: Kim Houng Joong, Kazuo Tahara, Kou Ajima, Koki Ueta, Toshiyuki Innami, Noriaki Hino, Taizo Miyazaki, Tomoyuki Hanyu, Kousaku Ohno
  • Patent number: 6653745
    Abstract: A power source apparatus includes a first switching element for controlling the power feed in the direction from a high-voltage battery to an inverter, and a second switching element for the power feed in the direction from the inverter to a low-voltage battery, and the voltage at the direct current side is controlled to be higher than that of the high-voltage battery when a battery controller for controlling the first and second switching elements breaks down.
    Type: Grant
    Filed: September 25, 2000
    Date of Patent: November 25, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Ryoso Masaki, Masahiko Amano, Mutsuhiro Mori, Hideki Miyazaki, Kazuo Tahara, Keiichi Mashino
  • Patent number: 6626002
    Abstract: In a motor driving unit controlled by switching to/from PWM control from/to PAM control so that the maximum limit of motor speed can be increased and, at the same time, the unit can be operated at maximum efficiency during steady-state operation, the motor speed is controlled by maintaining the DC voltage command to the converter control circuit constant, but altering the conduction ratio command value to the inverter control circuit when the load to the motor is low, and by maintaining the conduction ratio command to the inverter control circuit constant, but altering the DC voltage command to the converter control circuit. There is a commutating phase control circuit that alters the commutating timing of the coil of the motor, and the motor is so controlled that the efficiency reaches the maximum limit during steady-state operation and the speed reaches the maximum limit during high-speed operation.
    Type: Grant
    Filed: February 26, 2001
    Date of Patent: September 30, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Yasuo Notohara, Yukio Kawabata, Kazuo Tahara, Makoto Ishii, Yuhachi Takakura, Hiroshi Shinozaki
  • Patent number: 6603280
    Abstract: A converter module which receives an AC voltage, converts the AC voltage to a DC voltage, and outputs the DC voltage to a circuit for driving a motor. The converter module includes a switching device, a diode, and a control circuit which controls the DC voltage output by the converter module by controlling the switching device. The control circuit includes a plurality of DC voltage detection terminals which detect the DC voltage output by the converter module with respective different DC voltage detection gains, a selector which selects at least one of the DC voltage detection terminals in accordance with an external signal indicative of a speed of the motor, and outputs a DC voltage detection value, and a controller which controls the DC voltage output by the converter module in accordance with the DC voltage detection value output by the selector.
    Type: Grant
    Filed: January 18, 2001
    Date of Patent: August 5, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Yasuo Notohara, Yukio Kawabata, Kazuo Tahara, Makoto Ishii, Yuhachi Takakura
  • Patent number: 6577022
    Abstract: A hybrid drive type vehicle having a permanent magnet type synchronous motor can provide high torque characteristics in low revolution speed range of the engine and high power generation characteristics at high revolution speed range of the engine. The hybrid drive type vehicle includes an electric rotary machine being formed with a stator and a rotor. A field magnet of the rotor include a first field magnet and a second field magnet. The first and second field magnets are opposing with a magnetic pole of the stator and having a mechanism for varying a phase of a magnetic pole resulting from combination of the first and second field magnets relative to the magnetic pole of the first field magnet depending upon direction of a torque of the rotor.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: June 10, 2003
    Assignees: Hitachi, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Kim Houng Joong, Kazuo Tahara, Kou Ajima, Koki Ueta, Toshiyuki Innami, Noriaki Hino, Taizo Miyazaki, Tomoyuki Hanyu, Kousaku Ohno
  • Publication number: 20030102674
    Abstract: A hybrid drive type vehicle having a permanent magnet type synchronous motor can provide high torque characteristics in low revolution speed range of the engine and high power generation characteristics at high revolution speed range of the engine. The hybrid drive type vehicle includes an electric rotary machine being formed with a stator and a rotor. A field magnet of the rotor include a first field magnet and a second field magnet. The first and second field magnets are opposing with a magnetic pole of the stator and having a mechanism for varying a phase of a magnetic pole resulting from combination of the first and second field magnets relative to the magnetic pole of the first field magnet depending upon direction of a torque of the rotor.
    Type: Application
    Filed: January 23, 2003
    Publication date: June 5, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Kim Houng Joong, Kazuo Tahara, Kou Ajima, Koki Ueta, Toshiyuki Innami, Noriaki Hino, Taizo Miyazaki, Tomoyuki Hanyu, Kousaku Ohno
  • Patent number: 6541880
    Abstract: There is provided a linear motor, having an armature and a needle with magnetism, in which the armature has at least a magnetic pole of a first polarity having a first opposed part and another magnetic pole of a second polarity having a second opposed part; the needle is held by the first opposed part, and is further held by the second opposed part; and a distribution of magnetism of the needle according to a position in the movable direction thereof. In this way, a leak of a magnetic flux from pole teeth passing between the pole teeth of the armature is decreased to increase a thrust and braking force of the needle, which is thereby enabled to generate a greater or smaller thrust in a specific section or sections than the thrust during usual linear movement.
    Type: Grant
    Filed: February 27, 2001
    Date of Patent: April 1, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Okada, Kim Houng Joong, Kazuo Tahara, Kohji Maki, Kouki Yamamoto, Miyoshi Takahashi, Kenji Miyata, Ryoichi Takahata
  • Publication number: 20020175584
    Abstract: A permanent magnet type rotating electrical machine capable of reducing core loss due to armature reaction magnetic flux and making an effective use of reactance torque. A permanent magnet type rotating electrical machine comprising a first rotor core containing a permanent magnet and a second rotor core having a flux barrier without magnet, wherein a concave portion is provided between poles in the vicinity of outer surface the rotor core containing the permanent magnet and the length of the gap in the magnetic path on the q-axis side is increased to ensure easy passage of the magnetic path of the armature reaction magnetic flux on the reluctance torque rotor side, whereby a permanent magnet type rotating electrical machine delivering a large output can be obtained by making an effective use of reluctance torque.
    Type: Application
    Filed: October 4, 2001
    Publication date: November 28, 2002
    Inventors: Haruo Koharagi, Shinichi Wakui, Mamoru Kimura, Satoshi Kikuchi, Ryoichi Takahata, Kohji Maki, Kazuo Tahara, Kenji Miyata, Masashi Kitamura, Miyoshi Takahashi
  • Publication number: 20020175583
    Abstract: A permanent magnet type rotating electrical machine capable of reducing core loss due to armature reaction magnetic flux and making an effective use of reluctance torque. A permanent magnet type rotating electrical machine comprising a first rotor core equipped with a permanent magnet stored in a permanent magnet insertion hole, and a second rotor core having a reluctance magnetic circuit, wherein a concave portion is provided between poles in the vicinity of the outer surface of the first rotor core, and a flux barrier constituting the reluctance magnetic circuit of the second rotor core is arranged in a form different from the magnet insertion hole, whereby the magnetic path of the armature reaction magnetic flux is defined, and a permanent magnet type rotating electrical machine delivering a large output is obtained by making an effective use of reluctance torque.
    Type: Application
    Filed: October 4, 2001
    Publication date: November 28, 2002
    Inventors: Satoshi Kikuchi, Haruo Koharagi, Shinichi Wakui, Mamoru Kimura, Ryoichi Takahata, Kohji Maki, Kazuo Tahara, Kenji Miyata, Masashi Kitamura, Miyoshi Takahashi
  • Patent number: 6479956
    Abstract: The present invention supplies a position detection circuit, and a motor controller, that can not only obtain rotor position detection signals properly over the entire PWM control region, but also obtain these signals properly during PAM control. In a brushless motor controller based on the present invention to detect the magnetic pole position of the stator in the motor in accordance with the stator coil terminal voltages of multiple phases and control the energization of the stator coils, the comparison result information signal, after being obtained through comparison between the detected voltage values corresponding to the foregoing terminal voltages, and a reference voltage value, is directly entered into control circuits, then the position of the rotor in the motor is properly detected immediately after power-on switching, without a rotor position detection inhibition time interval being provided, and the motor is controlled properly.
    Type: Grant
    Filed: January 16, 2001
    Date of Patent: November 12, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Yukio Kawabata, Yasuo Notohara, Kazuo Tahara, Yuhachi Takakura, Makoto Ishii, Hiroshi Shinozaki