Patents by Inventor Sakae Nejo

Sakae Nejo 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: 10464605
    Abstract: To provide a vehicle steering control device capable of suppressing influence of a torque generated during driving support by an EPS device on steering of a steering wheel performed by a driver. The vehicle steering control device includes an EPS controller (first controller) that controls a speed reduction mechanism and a differential mechanism controller (second controller) that controls a differential mechanism. In addition, the vehicle steering control device has a first steering assist mode of assisting driver's steering and a second steering assist mode of performing steering independently from the driver's steering. In the second steering assist mode, the second controller controls the differential mechanism so as to cancel a torque applied to a rack-and-pinion side of the differential mechanism from the speed reduction mechanism controlled by the first controller.
    Type: Grant
    Filed: February 9, 2017
    Date of Patent: November 5, 2019
    Assignee: NSK LTD.
    Inventors: Tomonori Sato, Sakae Nejo, Nobuhiro Mitsuishi, Sumio Sugita
  • Patent number: 10315693
    Abstract: To provide a vehicle steering control device capable of alleviating discomfort caused by mismatch between a steering angle of a steering wheel and a steered angle of a drive wheel generated by automatic steering using an EPS device. The vehicle steering control device has a first steering assist mode of assisting driver's steering and a second steering assist mode of performing steering independently from the driver's steering. A second controller, performs phase shift suppression control to suppress a relative shift of a phase of a differential mechanism on a steering wheel side with respect to a reference phase on the steering wheel side of the differential mechanism corresponding to a phase on a rack-and-pinion side of the differential mechanism in the first steering assist mode.
    Type: Grant
    Filed: February 9, 2017
    Date of Patent: June 11, 2019
    Assignee: NSK LTD.
    Inventors: Nobuhiro Mitsuishi, Sakae Nejo, Sumio Sugita, Tomonori Sato
  • Publication number: 20190039650
    Abstract: To provide a vehicle steering control device capable of suppressing influence of a torque generated during driving support by an EPS device on steering of a steering wheel performed by a driver. The vehicle steering control device includes an EPS controller (first controller) that controls a speed reduction mechanism and a differential mechanism controller (second controller) that controls a differential mechanism. In addition, the vehicle steering control device has a first steering assist mode of assisting driver's steering and a second steering assist mode of performing steering independently from the driver's steering. In the second steering assist mode, the second controller controls the differential mechanism so as to cancel a torque applied to a rack-and-pinion side of the differential mechanism from the speed reduction mechanism controlled by the first controller.
    Type: Application
    Filed: February 9, 2017
    Publication date: February 7, 2019
    Applicant: NSK Ltd.
    Inventors: Tomonori SATO, Sakae NEJO, Nobuhiro MITSUISHI, Sumio SUGITA
  • Publication number: 20190023318
    Abstract: To provide a vehicle steering control device capable of alleviating discomfort caused by mismatch between a steering angle of a steering wheel and a steered angle of a drive wheel generated by automatic steering using an EPS device. The vehicle steering control device has a first steering assist mode of assisting driver's steering and a second steering assist mode of performing steering independently from the driver's steering. A second controller, performs phase shift suppression control to suppress a relative shift of a phase of a differential mechanism on a steering wheel side with respect to a reference phase on the steering wheel side of the differential mechanism corresponding to a phase on a rack-and-pinion side of the differential mechanism in the first steering assist mode.
    Type: Application
    Filed: February 9, 2017
    Publication date: January 24, 2019
    Applicant: NSK LTD.
    Inventors: Nobuhiro MITSUISHI, Sakae NEJO, Sumio SUGITA, Tomonori SATO
  • Patent number: 10059369
    Abstract: An electric power steering apparatus that has a torque sensor which detects a steering torque, and a motor control apparatus to control the motor which applies an assist torque, by which steering is assisted, to a steering system of a vehicle, including: a function that switches a control system of the motor between an angle control system to control an angle corresponding to an angle control command value of an automatic steering mode and a torque control system to control a torque corresponding to a torque control command value of a manual steering mode in accordance with a predetermined switching trigger, wherein the steering apparatus variably sets a gradual-changing time corresponding to a command value difference between the angle control command value and the torque control command value when switching from the angle control system to the torque control system by using a gradual-changing.
    Type: Grant
    Filed: June 9, 2016
    Date of Patent: August 28, 2018
    Assignee: NSK LTD.
    Inventors: Sakae Nejo, Tomonori Sato
  • Publication number: 20180154929
    Abstract: An electric power steering apparatus that has a torque sensor which detects a steering torque, and a motor control apparatus to control the motor which applies an assist torque, by which steering is assisted, to a steering system of a vehicle, including: a function that switches a control system of the motor between an angle control system to control an angle corresponding to an angle control command value of an automatic steering mode and a torque control system to control a torque corresponding to a torque control command value of a manual steering mode in accordance with a predetermined switching trigger, wherein the steering apparatus variably sets a gradual-changing time corresponding to a command value difference between the angle control command value and the torque control command value when switching from the angle control system to the torque control system by using a gradual-changing.
    Type: Application
    Filed: June 9, 2016
    Publication date: June 7, 2018
    Applicant: NSK LTD.
    Inventors: Sakae NEJO, Tomonori SATO
  • Patent number: 7849957
    Abstract: An electric power steering apparatus including a steering angle detection part that detects a steering angle of a steering wheel and outputs a steering angle signal, a steering control unit that controls a motor to give an assist torque to the steering wheel, an abnormality detection part that determines an abnormality of the steering angle detection part, and a motor angle detection part that detects a rotational angle of the motor. The steering control unit calculates a steering angle information based on at least the steering angle signal, and includes a signal storage part that stores the steering angle information. The steering control unit runs the motor continuously when the abnormality detection part detects the abnormality of the steering angle detection part until a vehicle stops or until the abnormality detection part determines that the steering angle signal returns to a normal state from the occurrence of the abnormality.
    Type: Grant
    Filed: July 16, 2007
    Date of Patent: December 14, 2010
    Assignee: NSK Ltd.
    Inventors: Takeshi Hara, Yong Wei, Hideaki Okazaki, Sakae Nejo
  • Patent number: 7586277
    Abstract: An electric power steering device changes the discontinuous non-linear characteristics in the duty ratio of the PWM signal versus motor current generated during steering wheel handle return into linear characteristics to suppress noise and provides a smooth and natural feeling steering. The electric control circuit (13) provided a current reference value calculator (22A) to calculate Iref, a current controller (22B) to obtain Vref2, a compensation adder (25) to obtain a duty D1, and a current discontinuity compensator (24) in order to obtain a duty D2. A motor drive circuit (35) including an H bridge circuit whose upper stage FET (1) is driven by the duty D1, and whose lower stage FED (3) paired with the upper stage FET (1), is driven by the duty D2 to allow forming a continuous linear characteristic in the duty ratio of the PWM signal versus the motor current.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: September 8, 2009
    Assignee: NSK Ltd.
    Inventors: Hideyuki Kobayashi, Toru Sakaguchi, Takeshi Hara, Sakae Nejo
  • Publication number: 20080078608
    Abstract: The present invention provides an electric power steering apparatus having: a motor that applies a steering assist power to a steering mechanism; a torque command value calculating part that calculates a torque command value based on a steering torque generated in a steering shaft and a vehicle speed; and a current command value calculating part that calculates a current command value of the motor based on the torque command value, and the motor is controlled based on the current command value, and the electric power steering apparatus further has: a yaw rate detecting part that detects or estimates a yaw rate of a vehicle; a target yaw rate calculating part that calculates a target yaw rate based on the vehicle speed and a steering angle; and a correcting part that calculates an amount of correction based on the yaw rate and the target yaw rate to correct the current command value.
    Type: Application
    Filed: July 16, 2007
    Publication date: April 3, 2008
    Applicant: NSK LTD.
    Inventors: Takeshi Hara, Yong Wei, Hideaki Okazaki, Sakae Nejo
  • Patent number: 7265509
    Abstract: The present invention provides an excellent electric power steering apparatus in which torque ripple caused by a quantization error of a current control system generated in case of slow steering state and steering holding state, namely, vibration and noise on a steering wheel can be suppressed. A current controller in which a steady state gain of feedback control is a finite value is used so as to be capable of suppressing the vibration and noise. Further, according to the present invention, a smoothing filter is included in a current control system so that the quantization error is smoothed so that the torque ripple is suppressed.
    Type: Grant
    Filed: July 15, 2005
    Date of Patent: September 4, 2007
    Assignee: NSK, Ltd.
    Inventors: Shuji Endo, Yuho Aoki, Kenji Mori, Toru Sakaguchi, Sakae Nejo, Hideaki Okazaki, Lilit Kovudhikulrungsri
  • Publication number: 20070120511
    Abstract: An electric power steering device changes the non-continuous, non-linear component in the duty ratio of the PWM signal versus motor current generated during steering wheel handle return into linear characteristics to suppress noise and allow a smooth and natural feeling during steering wheel handling. The electric control circuit (13) provided a current reference value calculator (22A) to calculate Iref a current controller (22B) to obtain Vref2, a compensation adder (25) to obtain a duty D1, and a current discontinuity compensator (24) in order to obtain a duty D2. A motor drive circuit (35) including an H bridge circuit whose upper stage FET (1) is driven by the duty D1, and whose lower stage FED (3) paired with the upper stage FET (1), is driven by the duty D2 to allow forming a continuous linear duty ratio characteristic in the duty ratio of the PWM signal versus the motor current.
    Type: Application
    Filed: December 3, 2004
    Publication date: May 31, 2007
    Applicant: NSK LTD
    Inventors: Hideyuki Kobayashi, Toru Sakaguchi, Takeshi Hara, Sakae Nejo
  • Publication number: 20060012323
    Abstract: The present invention provides an excellent electric power steering apparatus in which torque ripple caused by a quantization error of a current control system generated in case of slow steering state and steering holding state, namely, vibration and noise on a steering wheel can be suppressed. A current controller in which a steady state gain of feedback control is a finite value is used so as to be capable of suppressing the vibration and noise. Further, according to the present invention, a smoothing filter is included in a current control system so that the quantization error is smoothed so that the torque ripple is suppressed.
    Type: Application
    Filed: July 15, 2005
    Publication date: January 19, 2006
    Inventors: Shuji Endo, Yuho Aoki, Kenji Mori, Toru Sakaguchi, Sakae Nejo, Hideaki Okazaki, Lilit Kovudhikulrungsri