Nsk Corporation

Nsk Steering Co., Ltd.

Toshiyuki Onizuka

Shuji Endo

Kazuo Chikaraishi

Masaki Kuwahara

Kazuhiro Yoshida

Takayoshi Sugawara

Kouichi Satoh

Nobuhiko Andou

Takeshi Ishikawa

Takayuki Kobayashi

Yasuhiro Kawai

Takeshi Hara

Hui Chen

Kazuho Chikaraishi

Kouichi Sato

Koji Matsuda

There is provided a torque detecting device for providing a highly accurate torque signal, and an electric power steering device using the torque detecting device. A torque sensor is provided with a first coil pair and a second coil pair, which detect a relative displacement between an input shaft and an output shaft by corresponding the relative displacement to a change in impedance. Magnetization signal generating units supply exciting currents with different magnetization frequencies to the first coil pair and a second coil pair, respectively. The magnetization frequency difference is set to 3.5 kHz or higher. Moreover, low-pass filters for intercepting passage of a frequency equivalent to the magnetization frequency difference are deployed in signal processing circuits respectively.

Torque detecting device and electric power steering device

An abnormality diagnosing method is provided for a torque detecting device and an electric power steering device is provided using the torque detecting device. Immediately after the power supply is turned on and before steering auxiliary control is started, initial diagnosis is performed to determine that each monitoring block for monitoring an abnormality of a signal processing circuit constituting a torque detecting device operates normally. The initial diagnosis determines that a monitoring block is operating normally, by inputting a normal signal and an abnormal signal to the monitoring block alternately, and finding that the monitoring block carries out normal diagnosis when it receives the normal signal and that it carries out abnormal diagnosis when it receives the abnormal signal. Once all of the monitoring blocks are determined as normal, the steering auxiliary control based on a steering torque detected by the torque detecting device is started.

Abnormality diagnosing method for torque detecting device and electric power steering device

There are provided a torque detection apparatus with high reliability and an electric power steering system and a vehicle which use the torque detection apparatus. The torque detection apparatus () detects the torque based upon a difference in the terminal voltage of the pair of detection coils. In this situation, the torque detection apparatus () outputs two analog torque signals (analog main torque signal Tma and analog sub torque signal Tsa) to the ECU (), and outputs to the ECU () a digital communication signal S in which digital torque values obtained by converting the two analog torque signals to a digital format (main torque value Tm and sub torque value Ts) and diagnosis information Diag of the torque sensor circuit are superimposed.

Torque detection apparatus, electric power steering system and vehicle

A steering angle sensor detects a rotational angle of a steering system whose steering is assisted by driving of an electric motor via a reduction mechanism so as to calculate a steering angle of a steering wheel. The steering angle sensor includes: a sensor wheel operating simultaneously with rotation of a steering shaft; and an absolute angle calculating unit for calculating an absolute steering angle based on a steering angle signal from the sensor wheel. The sensor wheel includes a GMR element and a magnetizing portion which is arranged around the GMR element, and the rotational angle is detected by making two turns of the steering shaft as one cycle of the steering angle signal based on a change in resistance value of the GMR element obtained by changing a magnetic field direction according to a rotation of the magnetizing portion.

Steering angle sensor

In an electric power steering apparatus that urges a steering shaft or a rack shaft with an assist load using the drive force of a motor by a transmission mechanism via reduction gears, the reduction gears includes a rotation angle sensor assembled integrally therewith.

Electric power steering apparatus

The present invention relates to a motor-driven power steering apparatus structured such as to apply a steering assist force generated by a motor to a steering system of a motor vehicle or a vehicle in accordance with a rotation force of an electric motor on the basis of a steering torque detected by a torque sensor. Further, the invention relates to a rotation angle sensor for detecting a rotation angle of a steering shaft, a detected portion of the rotation angle sensor is provided within the speed reduction gear, and a detecting portion of the rotation angle sensor is provided in a radial direction of the steering shaft and in an outer side of a bearing in the speed reduction gear.

Motor-driven power steering apparatus

Electric power steering device

A torque sensor includes a pair of detection coils having the impedances that change in opposite directions of each other corresponding to a torque generated in a rotation shaft. An AC voltage is applied on a bridge circuit including a pair of detection coils and a pair of resistors, a differential voltage between AC voltages that appear on both ends of the pair of detection coils is detected and sent out as the torque signal, and a failure of a circuit component of the torque detecting circuit is judged based on the phase difference between the waveform of the AC voltage applied on the bridge circuit and the waveform of the differential voltage between AC voltages that appear on both ends of the pair of detection coils.

Torque sensor

A brushless DC-motor driving controller is provided which can significantly reduce torque fluctuations in the brushless DC motor. The brushless DC-motor driving controller uses a position detector, generates rotation-angle signals representing rotor-rotation angles or a part thereof in high resolution, uses the rotation-angle signals, and performs rectangular-wave driving. By using the rotation-angle signals, the brushless DC-motor driving controller compensates for electrical angles corresponding to commutation-position skews in rectangular-wave driving which are caused by armature reaction in a brushless DC-motor.

Brushless DC-motor driving controller

A torque sensor which does not require complicated neutral adjustment using a position adjustment mechanism or the like, which is capable of reducing cost and heat generation, improving reliability and realizing a one-system detection circuit. A torque sensor has a control calculating portion for varying operation timing of a coil for detecting torque and sample holding timing and a storage portion for storing an initial value of each element of the torque sensor. The torque is detected on the basis of sampling of transition voltage of the coil and a comparison with the initial value in the storage portion is made during detection of the torque is not being performed so that a failure of each element of the torque sensor is detected. Another torque sensor structured to detect torque in accordance with transient voltages which are generated in the portion in which coils and electric resistors are connected to each other is enabled to detect an abnormality of short circuit between a pair of the coils. At timing at which the torque is not detected, only either of rectangular-wave control voltages is applied to a transistor. At timing synchronized with falling of the control voltage, output voltage is A/D-converted and read. In accordance with whether or not output voltage is the same as power supply voltage, short circuit between the coils is detected.

In a torque sensor, coils and resistors constitute a bridge circuit, and the mutual connection part of the coils is connected to a power source via a coil drive unit. A control voltage, which varies in the square wave form, is supplied to the gate of a transistor in the coil drive unit so as to vary the voltage supplied to the coils in the square wave form. The output voltages which are the voltages between the coils and the resistors are input to the differential amplifier and the output voltage of the differential amplifier is held by a sample holding circuit to be supplied to a controller as the output voltage. The sample holding circuit holds the output voltage of the differential amplifier when the output voltages between the coils and the resistors are in the transient period. The controller detects the torque based on the output voltage of the sample holding circuit. An abnormal state monitoring unit is provided to detect an abnormal state of the coils.

Growing community of inventors

Maebashi, Japan

Toshiyuki Onizuka