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).
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Patent number: 10464605Abstract: 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: GrantFiled: February 9, 2017Date of Patent: November 5, 2019Assignee: NSK LTD.Inventors: Tomonori Sato, Sakae Nejo, Nobuhiro Mitsuishi, Sumio Sugita
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Patent number: 10315693Abstract: 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: GrantFiled: February 9, 2017Date of Patent: June 11, 2019Assignee: NSK LTD.Inventors: Nobuhiro Mitsuishi, Sakae Nejo, Sumio Sugita, Tomonori Sato
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Publication number: 20190039650Abstract: 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: ApplicationFiled: February 9, 2017Publication date: February 7, 2019Applicant: NSK Ltd.Inventors: Tomonori SATO, Sakae NEJO, Nobuhiro MITSUISHI, Sumio SUGITA
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Publication number: 20190023318Abstract: 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: ApplicationFiled: February 9, 2017Publication date: January 24, 2019Applicant: NSK LTD.Inventors: Nobuhiro MITSUISHI, Sakae NEJO, Sumio SUGITA, Tomonori SATO
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Patent number: 10059369Abstract: 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: GrantFiled: June 9, 2016Date of Patent: August 28, 2018Assignee: NSK LTD.Inventors: Sakae Nejo, Tomonori Sato
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Publication number: 20180154929Abstract: 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: ApplicationFiled: June 9, 2016Publication date: June 7, 2018Applicant: NSK LTD.Inventors: Sakae NEJO, Tomonori SATO
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Patent number: 7849957Abstract: 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: GrantFiled: July 16, 2007Date of Patent: December 14, 2010Assignee: NSK Ltd.Inventors: Takeshi Hara, Yong Wei, Hideaki Okazaki, Sakae Nejo
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Patent number: 7586277Abstract: 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: GrantFiled: December 3, 2004Date of Patent: September 8, 2009Assignee: NSK Ltd.Inventors: Hideyuki Kobayashi, Toru Sakaguchi, Takeshi Hara, Sakae Nejo
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Publication number: 20080078608Abstract: 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: ApplicationFiled: July 16, 2007Publication date: April 3, 2008Applicant: NSK LTD.Inventors: Takeshi Hara, Yong Wei, Hideaki Okazaki, Sakae Nejo
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Patent number: 7265509Abstract: 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: GrantFiled: July 15, 2005Date of Patent: September 4, 2007Assignee: NSK, Ltd.Inventors: Shuji Endo, Yuho Aoki, Kenji Mori, Toru Sakaguchi, Sakae Nejo, Hideaki Okazaki, Lilit Kovudhikulrungsri
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Publication number: 20070120511Abstract: 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: ApplicationFiled: December 3, 2004Publication date: May 31, 2007Applicant: NSK LTDInventors: Hideyuki Kobayashi, Toru Sakaguchi, Takeshi Hara, Sakae Nejo
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Publication number: 20060012323Abstract: 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: ApplicationFiled: July 15, 2005Publication date: January 19, 2006Inventors: Shuji Endo, Yuho Aoki, Kenji Mori, Toru Sakaguchi, Sakae Nejo, Hideaki Okazaki, Lilit Kovudhikulrungsri