Patents by Inventor Masafumi Sakamoto

Masafumi Sakamoto 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).

  • Publication number: 20030085681
    Abstract: In an industrial robot having a plurality of arms, each arm is coupled with other elements such as a mounting base, another arm, a robotic hand, and revolved by a motion of the revolute joint. The revolute joint has a rotary electric connecting structure such as a slip ring or a rotary transformer which can be rotated endlessly. Electric powers for driving motors by which the arms are revolved and control signals for controlling the driving of the motors are supplied or transmitted through the rotary electric connecting structure, so that the arms can be rotated endlessly without twisting or breaking of electric cables.
    Type: Application
    Filed: October 9, 2002
    Publication date: May 8, 2003
    Inventors: Masafumi Sakamoto, Kaoru Endo, Katsuhiro Yamazoe, Takahiro Kobiki
  • Patent number: 6548923
    Abstract: The permeance between the small teeth provided on the stator magnetic pole and the rotor magnetic pole may be varied regularly according to the rotation of the rotor. The small stator teeth provided on the tip end of each stator magnetic pole are divided into sets of two or three small stator teeth and at least one pitch of the adjacent teeth is different from the other pitch of the other adjacent teeth, so that the vector sum of the quaternary harmonics of permeance in each set is substantially zero.
    Type: Grant
    Filed: March 29, 2001
    Date of Patent: April 15, 2003
    Assignee: Japan Servo Co., Ltd.
    Inventors: Kazuo Ohnishi, Masafumi Sakamoto, Koki Isozaki
  • Patent number: 6545376
    Abstract: In the three-phase hybrid type stepping motor according to the present invention, the small stator teeth formed on the tip end of the stator pole are classified to sets of two or three small teeth, the third harmonic vector sum of the permeances of the small teeth in each set is determine to substantially zero, and the third, fifth and sixth harmonic vector sum of the permeances of the small teeth of the sets is determine to substantially zero, under the consideration that the permeances between the small teeth of the stator magnetic pole and the rotor are varied according to the rotation of the rotor and that the permeances are varied regularly.
    Type: Grant
    Filed: May 21, 2001
    Date of Patent: April 8, 2003
    Assignee: Japan Servo Co., Ltd.
    Inventors: Kazuo Ohnishi, Masafumi Sakamoto, Koki Isozaki
  • Publication number: 20030062779
    Abstract: A three-phase hybrid type stepping motor of the present invention comprises a stator, a rotor arranged concentrically with the stator and with an air gap therebetween, six stator poles extending radially and formed at a regular pitch on the inner peripheral surface of an annular stator yoke, each of the stator poles having a plurality of small stator teeth at the tip end thereof, the rotor having two splitted rotor elements and a permanent magnet held therebetween and magnetized so as to form N and S poles in the axial direction thereof, fifty of small rotor teeth formed at a regular pitch on the outer peripheral surface of each of the rotor elements, the two splitted rotor elements being shifted from each other in angular position by a ½ pitch of the small rotor teeth, wherein a permeance distribution of the small stator teeth is a vernier pitch balanced by a six or three order harmonic wave, and a tooth width ratio of the small rotor teeth with the small stator teeth is set to 0.35-0.45.
    Type: Application
    Filed: February 22, 2002
    Publication date: April 3, 2003
    Applicant: Japan Servo Co., Ltd.
    Inventors: Kazuo Ohnishi, Toshimi Abukawa, Masafumi Sakamoto, Koki Isozaki
  • Publication number: 20030052552
    Abstract: In a permanent magnet type three-phase stepping motor having a stator having 3L pieces of stator pole and a rotor having a permanent magnet magnetized so as to form a plurality (Nr) of N and S pole pairs, wherein a condition of 0.3≦{(Nr/&pgr;)(Ws+Wr)/(Ds+Dr)}≦0.5 is established, where L is an integer not less than 1, Nr is L(3n+1), n is an integer not less than 1, Ds is an inner diameter of the stator, Dr is an outer diameter of the rotor, Ws is a width of the stator pole tooth, and Wr is a width of the rotor tooth.
    Type: Application
    Filed: July 17, 2002
    Publication date: March 20, 2003
    Applicant: Japan Servo Co. Ltd.
    Inventor: Masafumi Sakamoto
  • Patent number: 6504272
    Abstract: Disclosed is a multi-phase electric rotating machine having toroidal coils that consists of a stator having the number P of stator units (P is integer, P>2), a rotor facing the stator with a predetermined air gap. Each of stator units is formed of a pair of stator iron cores and a toroidal coil that concentrically gets caught therebetween. Each of the stator iron cores has the number Ns of stator teeth formed around an inner circumference at equal pitch Ps, the pair of stator iron cores are arranged such that the stator teeth are shifted by ½ of the pitch Ps. The stator units are arranged in the axial direction such that the stator teeth of the units are shifted by ½P of the pitch Ps. The rotor consists of rotor magnetic bodies and a permanent magnet. Rotor teeth of Nr in the total number are arranged around the outer circumference of the rotor. The rotor teeth consist of k pair of N and S polar rotor teeth groups (k is integer, k≧1) arranged in the rotating direction.
    Type: Grant
    Filed: November 29, 2000
    Date of Patent: January 7, 2003
    Assignee: Japan Servo Co., Ltd.
    Inventor: Masafumi Sakamoto
  • Publication number: 20020190585
    Abstract: Disclosed is a three-phase toroidal coil type electric rotating machine including a rotor that comprises a cylindrical permanent magnet having M pairs of N-poles and S-poles that are alternatively arranged around a rotor axis, and a stator that comprises three stator units stacked in an axial direction around the cylindrical permanent magnet. Each stator unit has a pair of stator magnetic poles and a toroidal coil sandwiched therebetween. Each stator magnetic pole has M pieces of claw poles extending in the axial direction. The claw poles of the stator magnetic poles are in mesh with each other inside the toroidal coil. The toroidal coils are connected as a delta connection. The positional relationship between the claw poles and the cylindrical permanent magnet is determined such that the phase differences among speed electromotive forces caused in the toroidal coils are 120 degrees (electrical angle) between any two of the three terminals.
    Type: Application
    Filed: June 17, 2002
    Publication date: December 19, 2002
    Applicant: JAPAN SERVO CO., LTD.
    Inventor: Masafumi Sakamoto
  • Publication number: 20020175581
    Abstract: A permanent magnet motor having a stator and a permanent magnet rotor facing the stator with a gap therebetween, the stator having a plurality of stator magnetic poles extending radially toward a peripheral surface of the rotor, s number of small stator teeth formed on a tip end of each of the magnetic poles, and exciting windings of m phases wound around the stator magnetic poles. The rotor having a cylindrical permanent magnet having pieces of N pole and pieces of S pole arranged alternately in a peripheral direction thereof at equal pitches, wherein a pitch of the small stator teeth is 1±1/(2 ms) times larger than a pitch of the rotor magnetic pole pairs. The width of the small stator tooth is 37˜47% of the magnetic pole pitch. A depth of the groove formed between the adjacent small stator teeth is more than 15 times larger than the length of the air gap between the stator and the rotor.
    Type: Application
    Filed: March 22, 2002
    Publication date: November 28, 2002
    Applicant: Japan Servo Co., Ltd.
    Inventors: Kazuo Ohnishi, Masafumi Sakamoto, Noriyoshi Kikuchi
  • Patent number: 6477918
    Abstract: For driving an actuator which is optimum for and practical in use as a three-dimensionally positioning apparatus for a monitoring camera, a disco-lighting, an antenna, a multi-axis (multi-articular) robot, etc., an inner rotor type rotary electric machine is provided having a coaxial output hollow shaft with a reduction gear and a slip ring, including a hollow rotation shaft; a reduction gear for reducing an output of the inner rotor type rotary electric machine and extracting an output through a hollow shaft of the reduction gear coaxially with the hollow rotation shaft; and a slip ring provided in a hollow portion or an output portion of the reduction gear. Instead of the inner rotor type rotary electric machine, a similar outer rotor type rotary electric machine may be used.
    Type: Grant
    Filed: April 6, 2001
    Date of Patent: November 12, 2002
    Assignee: Japan Servo Co., Ltd.
    Inventor: Masafumi Sakamoto
  • Publication number: 20020158521
    Abstract: A magnet type stepping motor which has (1) a stator with three-phase stator windings, and 6m pieces of stator main pole arranged side by side, where m is an integer and ≧1, the stator windings of one phase are wound around every two stator main poles among the 6m pieces of the stator main pole, wherein when the stator windings of one phase are excited with a direct current, m pieces of N pole and M pieces of S pole are formed alternately on the Gm pieces of stator main pole, and (2) a rotor of a cylindrical permanent magnet magnetized in the circumferential direction to form Z/2 pieces of N pole and Z/2 pieces of S pole alternately, where Z is the number of rotor poles.
    Type: Application
    Filed: June 13, 2002
    Publication date: October 31, 2002
    Applicant: Japan Servo Co., Ltd.
    Inventor: Masafumi Sakamoto
  • Patent number: 6460889
    Abstract: A stopper 1 is fixedly mounted on and projects from an outer surface of that portion of a side frame 7 disposed in the vicinity of a front wheel 14. A reinforcement 2 is mounted on an inner surface of that portion of the side frame 7, on which the stopper 1 is mounted, thereby reinforcing the stopper 1. At the time of a collision of a vehicle, a rear side 17 of an outer periphery of the front wheel 14 strikes against the stopper 1, and also the movement of the stopper 1 is prevented by the reinforcement 2, thereby limiting the movement of the front wheel 14. Therefore, the deformation of the side frame 7 and so on toward the vehicle frame is reduced.
    Type: Grant
    Filed: November 27, 1998
    Date of Patent: October 8, 2002
    Assignee: Isuzu Motors Limited
    Inventors: Yoshitaka Iyanagi, Katsumasa Nagano, Akira Oda, Hiroyuki Nagae, Masafumi Sakamoto
  • Publication number: 20020079749
    Abstract: In the three-phase hybrid type stepping motor according to the present invention, the small stator teeth formed on the tip end of the stator pole are classified to sets of two or three small teeth, the third harmonic vector sum of the permeances of the small teeth in each set is determine to substantially zero, and the third, fifth and sixth harmonic vector sum of the permeances of the small teeth of the sets is determine to substantially zero, under the consideration that the permeances between the small teeth of the stator magnetic pole and the rotor are varied according to the rotation of the rotor and that the permeances are varied regularly.
    Type: Application
    Filed: May 21, 2001
    Publication date: June 27, 2002
    Applicant: Japan Servo Co. Ltd.
    Inventors: Kazuo Ohnishi, Masafumi Sakamoto, Koki Isozaki
  • Publication number: 20020079750
    Abstract: Disclosed is a permanent magnet type twelve-pole stepping motor of an inner rotor type or an outer rotor type. A stator comprises an annular shaped yoke portion, a stator iron-core having twelve stator main poles each having a plurality of small teeth on the tip end thereof and stator coils wound in the stator iron-core as three-phase winding. The stator rotatably supports a hybrid type rotor having a cylindrical permanent magnet that is sandwiched between a pair of rotors each having pole teeth around the circumferential surface to be opposite to the small teeth. Second, third, fourth and fifth harmonic components are removed by composing cogging torque of the respective phases by means of the three-phase twelve-pole construction. Any one harmonic component of the cogging torque among the second to fifth harmonic components is independently erased by making a difference between the small teeth pitch and the rotor teeth pitch, thereby the selected harmonic component is doubly erased.
    Type: Application
    Filed: December 3, 2001
    Publication date: June 27, 2002
    Applicant: JAPAN SERVO CO., LTD.
    Inventors: Masafumi Sakamoto, Noriyoshi Kikuchi, Toru Kobayashi
  • Patent number: 6359349
    Abstract: A rotor composite type three-phase stepping motor having a stator consisting of two stator elements each having 6n pieces of stator magnetic pole with Ns pieces of pole tooth formed on the tip end of each stator magnetic pole piece, and a permanent magnet held by the two stator elements therebetween, a rotor of magnetic material arranged so as to face to a periphery of the stator through an air gap, Nr pieces of pole tooth being formed on a periphery of the rotor, and exciting windings wound around each stator magnetic pole piece of the stator elements consisting of two sets of three-phase windings each wound around 3n pieces of stator magnetic pole among the 6n pieces of stator magnetic pole.
    Type: Grant
    Filed: October 12, 2000
    Date of Patent: March 19, 2002
    Assignee: Japan Servo Co., Ltd.
    Inventor: Masafumi Sakamoto
  • Publication number: 20020024267
    Abstract: There is provided a motor-driven system which realizes an optimum driving mode for an electric automobile, a robot carrier car, a drum of a copying machine, etc., and a motor-driven system having a function as an optimum actuator for such driving.
    Type: Application
    Filed: July 27, 2001
    Publication date: February 28, 2002
    Applicant: JAPAN SERVO CO., LTD.
    Inventor: Masafumi Sakamoto
  • Publication number: 20020008375
    Abstract: A stopper 1 is fixedly mounted on and projects from an outer surface of that portion of a side frame 7 disposed in the vicinity of a front wheel 14. A reinforcement 2 is mounted on an inner surface of that portion of the side frame 7, on which the stopper 1 is mounted, thereby reinforcing the stopper 1. At the time of a collision of a vehicle, a rear side 17 of an outer periphery of the front wheel 14 strikes against the stopper 1, and also the movement of the stopper 1 is prevented by the reinforcement 2, thereby limiting the movement of the front wheel 14. Therefore, the deformation of the side frame 7 and so on toward the vehicle frame is reduced.
    Type: Application
    Filed: November 27, 1998
    Publication date: January 24, 2002
    Inventors: YOSHITAKA IYANAGI, KATSUMASA NAGANO, AKIRA ODA, HIROYUKI NAGAE, MASAFUMI SAKAMOTO
  • Publication number: 20010052735
    Abstract: To drive an actuator which is optimum for and practical in use as a three-dimensionally positioning apparatus for a monitoring camera, a disco-lighting, an antenna, a multi-axis (multi-articular) robot, etc., there is provided an inner rotor type rotary electric machine having a coaxial output hollow shaft with a reduction gear and a slip ring, comprising: a hollow rotation shaft; a reduction gear for reducing an output of the inner rotor type rotary electric machine and extracting an output through a hollow shaft of the reduction gear coaxially with the hollow rotation shaft; and a slip ring provided in a hollow portion or an output portion of the reduction gear. Instead of the inner rotor type rotary electric machine, a similar outer rotor type rotary electric machine may be used.
    Type: Application
    Filed: April 6, 2001
    Publication date: December 20, 2001
    Applicant: JAPAN SERVO CO., LTD.
    Inventor: Masafumi Sakamoto
  • Patent number: 6329729
    Abstract: A magnet type stepping motor which has (1) a stator with three-phase stator windings, and 6m pieces of stator main pole arranged side by side, where m is an integer and ≧1, the stator windings of one phase are wound around every two stator main poles among the 6m pieces of the stator main pole, wherein when the stator windings of one phase are excited with a direct current, m pieces of N pole and M pieces of S pole are formed alternately on the 6m pieces of stator main pole, and (2) a rotor of a cylindrical permanent magnet magnetized in the circumferential direction to form Z/2 pieces of N pole and Z/2 pieces of S pole alternately, where Z is the number of rotor poles.
    Type: Grant
    Filed: August 16, 2000
    Date of Patent: December 11, 2001
    Assignee: Japan Servo Co. Ltd.
    Inventor: Masafumi Sakamoto
  • Patent number: 6320347
    Abstract: A rotor composite type three-phase stepping motor having a stator consisting of two stator elements each having 6 n pieces of stator magnetic pole with Ns pieces of pole tooth formed on the tip end of each stator magnetic pole piece, and a permanent magnet held by the two stator elements therebetween, a rotor of magnetic material arranged so as to face to a periphery of the stator through an air gap, Nr pieces of pole tooth being formed on a periphery of the rotor, and exciting windings wound around each stator magnetic pole piece of the stator elements consisting of two sets of three-phase windings each wound around 3n pieces of stator magnetic pole among the 6 n pieces of stator magnetic pole.
    Type: Grant
    Filed: October 12, 2000
    Date of Patent: November 20, 2001
    Assignee: Japan Servo Co., Ltd.
    Inventor: Masafumi Sakamoto
  • Publication number: 20010038249
    Abstract: The permeance between the small teeth provided on the stator magnetic pole and the rotor magnetic pole may be varied regularly according to the rotation of the rotor. The small stator teeth provided on the tip end of each stator magnetic pole are divided into sets of two or three small stator teeth and at least one pitch of the adjacent teeth is different from the other pitch of the other adjacent teeth, so that the vector sum of the quaternary harmonics of permeance in each set is substantially zero.
    Type: Application
    Filed: March 29, 2001
    Publication date: November 8, 2001
    Applicant: Japan Servo Co., Ltd.
    Inventors: Kazuo Ohnishi, Masafumi Sakamoto, Koki Isozaki